Simplified the logic. It doesn't change the behaviour.

The purpose of this interface is to highlight developers that in order
to cleanly get ride of the classes that implement the interface, they
need to call the `destroy` method.

This interface doesn't actually enforce calling `destroy`, but hopefully
makes the omission more notorious.

Client versions have the form `MAJOR.MINOR.PATCH`. Client tags are the
same but with a 'v' prefix.

Bumps [browserslist](https://github.com/browserslist/browserslist) from 4.16.3 to 4.16.6.
- [Release notes](https://github.com/browserslist/browserslist/releases)
- [Changelog](https://github.com/browserslist/browserslist/blob/main/CHANGELOG.md)
- [Commits](https://github.com/browserslist/browserslist/compare/4.16.3...4.16.6)
Signed-off-by: dependabot[bot] <support@github.com>

`create-github-release.js` had an implicit assumption that it was run
before the new version was tagged. It would generate the change log
based on PRs merged since the most recent tag. However Jenkins now runs
this script after the tag is created. As a result the change log was
always empty.

Fix the issue by explicitly passing the previous version as an argument
to the script so that it doesn't matter whether the new version has been
tagged or not.

See https://sass-lang.com/documentation/breaking-changes/slash-div for details

Bumps [@hypothesis/frontend-shared](https://github.com/hypothesis/frontend-shared) from 2.0.0 to 2.1.0.
- [Release notes](https://github.com/hypothesis/frontend-shared/releases)
- [Changelog](https://github.com/hypothesis/frontend-shared/blob/main/CHANGELOG.md)
- [Commits](https://github.com/hypothesis/frontend-shared/compare/v2.0.0...v2.1.0)
Signed-off-by: dependabot[bot] <support@github.com>

Bumps [@babel/core](https://github.com/babel/babel/tree/HEAD/packages/babel-core) from 7.14.2 to 7.14.3.
- [Release notes](https://github.com/babel/babel/releases)
- [Changelog](https://github.com/babel/babel/blob/main/CHANGELOG.md)
- [Commits](https://github.com/babel/babel/commits/v7.14.3/packages/babel-core)
Signed-off-by: dependabot[bot] <support@github.com>

Bumps [axe-core](https://github.com/dequelabs/axe-core) from 4.2.0 to 4.2.1.
- [Release notes](https://github.com/dequelabs/axe-core/releases)
- [Changelog](https://github.com/dequelabs/axe-core/blob/v4.2.1/CHANGELOG.md)
- [Commits](https://github.com/dequelabs/axe-core/compare/v4.2.0...v4.2.1)
Signed-off-by: dependabot[bot] <support@github.com>

Bumps [@sentry/browser](https://github.com/getsentry/sentry-javascript) from 6.4.0 to 6.4.1.
- [Release notes](https://github.com/getsentry/sentry-javascript/releases)
- [Changelog](https://github.com/getsentry/sentry-javascript/blob/master/CHANGELOG.md)
- [Commits](https://github.com/getsentry/sentry-javascript/compare/6.4.0...6.4.1)
Signed-off-by: dependabot[bot] <support@github.com>

Bumps [aws-sdk](https://github.com/aws/aws-sdk-js) from 2.907.0 to 2.912.0.
- [Release notes](https://github.com/aws/aws-sdk-js/releases)
- [Changelog](https://github.com/aws/aws-sdk-js/blob/master/CHANGELOG.md)
- [Commits](https://github.com/aws/aws-sdk-js/compare/v2.907.0...v2.912.0)
Signed-off-by: dependabot[bot] <support@github.com>

Bumps [@actions/core](https://github.com/actions/toolkit/tree/HEAD/packages/core) from 1.2.7 to 1.3.0.
- [Release notes](https://github.com/actions/toolkit/releases)
- [Changelog](https://github.com/actions/toolkit/blob/main/packages/core/RELEASES.md)
- [Commits](https://github.com/actions/toolkit/commits/HEAD/packages/core)
Signed-off-by: dependabot[bot] <support@github.com>

Bumps [postcss](https://github.com/postcss/postcss) from 8.2.15 to 8.3.0.
- [Release notes](https://github.com/postcss/postcss/releases)
- [Changelog](https://github.com/postcss/postcss/blob/main/CHANGELOG.md)
- [Commits](https://github.com/postcss/postcss/compare/8.2.15...8.3.0)
Signed-off-by: dependabot[bot] <support@github.com>

Bumps [sass](https://github.com/sass/dart-sass) from 1.32.13 to 1.34.0.
- [Release notes](https://github.com/sass/dart-sass/releases)
- [Changelog](https://github.com/sass/dart-sass/blob/master/CHANGELOG.md)
- [Commits](https://github.com/sass/dart-sass/compare/1.32.13...1.34.0)
Signed-off-by: dependabot[bot] <support@github.com>

Bumps [eslint](https://github.com/eslint/eslint) from 7.26.0 to 7.27.0.
- [Release notes](https://github.com/eslint/eslint/releases)
- [Changelog](https://github.com/eslint/eslint/blob/master/CHANGELOG.md)
- [Commits](https://github.com/eslint/eslint/compare/v7.26.0...v7.27.0)
Signed-off-by: dependabot[bot] <support@github.com>

We have been replacing default exports from services. We only allow
default exports on preact components.

We have been replacing default exports from services. We only allow
default exports on preact components.

The styles in `notebook.scss` really belonged to the `NotebookModal`
component. I moved these styles into their own file in the component
folder.

The are no changes in the look an feel. The styles were copied almost
verbatim from `notebook.scss`.

Update the Alpine version used by the Docker container that Jenkins
uses. This updates Node from v12 to v14 amongst other changes.

Recent releases on GitHub do not have the expected release notes,
although the `create-github-release.js` script appears to be running
without errors.

Add logging to the script to show what the release description and
version should be before asking GitHub to create it.

Per the example in https://github.com/octokit/core.js/#rest-api-example
the value for the `auth` property in the `Octokit` constructor is now just
the personal access token, not `token $TOKEN`. The old format still
works with a recently generated token though.

To test:

```sh
export GITHUB_TOKEN=$TOKEN
node scripts/generate-change-list.js $PREV_CLIENT_VERSION
```

Where `$TOKEN` is a token generated at https://github.com/settings/tokens and
`$PREV_CLIENT_VERSION` is the previous released version of the client to
use as a starting point for the change list.

This PR ensures that the annotation header is always shown, even if the
top-level annotation is hidden by a filter. The annotation header
contains the document target. This information is specially important in
the context of the notebook, where annotations from different documents
are displayed together.

I created a wrapper around the `AnnotationHeader` component. I couldn't
use it directly because I needed a couple of methods from the store to
mimic 100% the same behaviour as when `AnnotationHeader` is called
through `Annotation` component.

1. Added an option (`allowFlagging`) in the service configuration to
   enable/disable flagging.

2. Added logic in `AnnoationActionBar` component to hide the flag icon
   if the service configuration has the option `allowFlagging`.

Closes https://github.com/hypothesis/product-backlog/issues/1126

These methods are short and only called in one place, so there is not a
lot of value in having them as separate methods.

Follow up the initial conversion of `StreamerService` from a function to
a class but converting instance fields from local variables in the
constructor to properties and methods from closures to object methods.

In the process some unused public APIs were removed:

 - Remove the public `reconnect` method

 - Remove the public `configMessages` field

 - Rename the internal `_connect` helper to `_reconnect` and make it
   always close the existing connection if open

Bumps [aws-sdk](https://github.com/aws/aws-sdk-js) from 2.903.0 to 2.907.0.
- [Release notes](https://github.com/aws/aws-sdk-js/releases)
- [Changelog](https://github.com/aws/aws-sdk-js/blob/master/CHANGELOG.md)
- [Commits](https://github.com/aws/aws-sdk-js/compare/v2.903.0...v2.907.0)
Signed-off-by: dependabot[bot] <support@github.com>

Bumps [@hypothesis/frontend-shared](https://github.com/hypothesis/frontend-shared) from 1.13.0 to 2.0.0.
- [Release notes](https://github.com/hypothesis/frontend-shared/releases)
- [Changelog](https://github.com/hypothesis/frontend-shared/blob/main/CHANGELOG.md)
- [Commits](https://github.com/hypothesis/frontend-shared/compare/v1.13.0...v2.0.0)
Signed-off-by: dependabot[bot] <support@github.com>

Bumps [@babel/preset-env](https://github.com/babel/babel/tree/HEAD/packages/babel-preset-env) from 7.14.1 to 7.14.2.
- [Release notes](https://github.com/babel/babel/releases)
- [Changelog](https://github.com/babel/babel/blob/main/CHANGELOG.md)
- [Commits](https://github.com/babel/babel/commits/v7.14.2/packages/babel-preset-env)
Signed-off-by: dependabot[bot] <support@github.com>

Bumps [sass](https://github.com/sass/dart-sass) from 1.32.12 to 1.32.13.
- [Release notes](https://github.com/sass/dart-sass/releases)
- [Changelog](https://github.com/sass/dart-sass/blob/master/CHANGELOG.md)
- [Commits](https://github.com/sass/dart-sass/compare/1.32.12...1.32.13)
Signed-off-by: dependabot[bot] <support@github.com>

Bumps [postcss](https://github.com/postcss/postcss) from 8.2.14 to 8.2.15.
- [Release notes](https://github.com/postcss/postcss/releases)
- [Changelog](https://github.com/postcss/postcss/blob/main/CHANGELOG.md)
- [Commits](https://github.com/postcss/postcss/compare/8.2.14...8.2.15)
Signed-off-by: dependabot[bot] <support@github.com>

Bumps [katex](https://github.com/KaTeX/KaTeX) from 0.13.9 to 0.13.11.
- [Release notes](https://github.com/KaTeX/KaTeX/releases)
- [Changelog](https://github.com/KaTeX/KaTeX/blob/master/CHANGELOG.md)
- [Commits](https://github.com/KaTeX/KaTeX/compare/v0.13.9...v0.13.11)
Signed-off-by: dependabot[bot] <support@github.com>

Bumps [@babel/core](https://github.com/babel/babel/tree/HEAD/packages/babel-core) from 7.14.0 to 7.14.2.
- [Release notes](https://github.com/babel/babel/releases)
- [Changelog](https://github.com/babel/babel/blob/main/CHANGELOG.md)
- [Commits](https://github.com/babel/babel/commits/v7.14.2/packages/babel-core)
Signed-off-by: dependabot[bot] <support@github.com>

Bumps [@sentry/browser](https://github.com/getsentry/sentry-javascript) from 6.3.6 to 6.4.0.
- [Release notes](https://github.com/getsentry/sentry-javascript/releases)
- [Changelog](https://github.com/getsentry/sentry-javascript/blob/master/CHANGELOG.md)
- [Commits](https://github.com/getsentry/sentry-javascript/compare/6.3.6...6.4.0)
Signed-off-by: dependabot[bot] <support@github.com>

- Observe changes in `enable-annotation` attribute. Currently, if an
  existing iframe adds the attribute it won't be detected.

- `sidebar` or `notebook` iframes are shadow DOMed so they are not
  returned by `querySelector...` or `getElement...` (from elements
  outside the shadow root). Therefore, it is not necessary to filter
  these iframes out.

Specify the type of `window.PDFViewerApplication` in src/types/pdfjs.js
add various missing properties required by `PDFIntegration` as well as
adding checks for potentially null/undefined values that were missing
previously.

 - Add a fallback for older versions of PDF.js where `PDFViewerApplication`
   did not have an `appConfig` property [1]
 - Add a missing check for `getPageView` returning `null`

Fixes https://github.com/hypothesis/product-backlog/issues/1205

[1] The property was introduced in https://github.com/mozilla/pdf.js/commit/b6c74f20561b04573cd00dd924484be7f80a09ce

Add a temporary class name prefix to the local `Panel` component styles.

This will avoid conflicts with the styling for the new `Panel` component
in the `frontend-shared` package.

In the future:

* This local `Panel` will be supplanted by the shared variant, and
* Shared component classnames will be prefixed to avoid future conflicts

All of the components use selector methods now instead of accessing the
store's internal state directly.