Devise a way to "extend" a common base playground app with local-app
routes and patterns

In the soon-future, we'll want to extract the common bits of the
UI Playground app to the `frontend-shared` repository. This is step 1.

Only `@forward` specific mixins and create a function to retrieve
color settings out of the `_config` partial

If opening the login popup window using `window.open` fails or succeeds
but fails to return a `Window` reference to the caller then show a more
helpful error message.

There are various rare scenarios (browser bugs, browser extensions)
which might cause this to happen. There is not a whole lot we can do to
recover, but at least we can show a better error message.

Use `IconButton` in `ShareAnnotationsPanel` and
`AnnotationShareControl`, with custom styling to make
the buttons pair well with a text input.

It would be ideal to create a design pattern from the
combo of the input + button in the future.

Replace uses of `Button` in the Thread component and adjust
styling for stronger alignment in both desktop and touch interfaces.

Add a full novel as a test document for testing performance and
behaviors related to long PDF documents, such as re-anchoring when pages
are rendered and un-rendered while scrolling through the document.

We try to keep example PDFs small to avoid bloating the git repository, but
this one is on the larger side (~700KB) due to its length.

This PDF was produced by downloading the EPUB version of the novel [1]
from Project Gutenberg and then converting it to a PDF using Calibre [2]

[1] https://www.gutenberg.org/ebooks/64317
[2] https://calibre-ebook.com

The types for `SortBy` and `SortOrder` were swapped.

This matches how Prettier formats self-closing JSX tags and makes
expressions such as `<Widget expanded />` more readable.

 - Indent children by two spaces

 - Handle boolean props closer to how we normally set them in JSX by omitting
   them if false and including them without explicit values if true.
   This assumes that boolean props default to false. If there is a
   scenario in future where this is not the case, this behavior may need
   to be configurable.

 - Handle `bigint` numeric values. We have no use case for this, but
   TypeScript pointed out that it wasn't handled.

 - Add JSDoc comments

* Break out most private mixins into `_base`
* Provide `IconButton`, `LabeledButton`, `LinkButton` as public mixins
* Establish colors for all variants in `_config`
* Extend mixins to support sizes and more variants
* Update `TopBar` and `SearchInput`, as custom styling no longer
  necessary; remove those custom styles

Bumps [@sentry/browser](https://github.com/getsentry/sentry-javascript) from 6.2.3 to 6.2.5.
- [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/6.2.3...6.2.5)
Signed-off-by: dependabot[bot] <support@github.com>

Bumps [aws-sdk](https://github.com/aws/aws-sdk-js) from 2.874.0 to 2.880.0.
- [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/v2.874.0...v2.880.0)
Signed-off-by: dependabot[bot] <support@github.com>

Bumps [postcss](https://github.com/postcss/postcss) from 8.2.8 to 8.2.9.
- [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/8.2.8...8.2.9)
Signed-off-by: dependabot[bot] <support@github.com>

Bumps [core-js](https://github.com/zloirock/core-js/tree/HEAD/packages/core-js) from 3.9.1 to 3.10.0.
- [Release notes](https://github.com/zloirock/core-js/releases)
- [Changelog](https://github.com/zloirock/core-js/blob/master/CHANGELOG.md)
- [Commits](https://github.com/zloirock/core-js/commits/v3.10.0/packages/core-js)
Signed-off-by: dependabot[bot] <support@github.com>

Bumps [classnames](https://github.com/JedWatson/classnames) from 2.2.6 to 2.3.1.
- [Release notes](https://github.com/JedWatson/classnames/releases)
- [Changelog](https://github.com/JedWatson/classnames/blob/master/HISTORY.md)
- [Commits](https://github.com/JedWatson/classnames/commits)
Signed-off-by: dependabot[bot] <support@github.com>

Bumps [sinon](https://github.com/sinonjs/sinon) from 9.2.4 to 10.0.0.
- [Release notes](https://github.com/sinonjs/sinon/releases)
- [Changelog](https://github.com/sinonjs/sinon/blob/master/CHANGELOG.md)
- [Commits](https://github.com/sinonjs/sinon/compare/v9.2.4...v10.0.0)
Signed-off-by: dependabot[bot] <support@github.com>

Bumps [aws-sdk](https://github.com/aws/aws-sdk-js) from 2.874.0 to 2.879.0.
- [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/v2.874.0...v2.879.0)
Signed-off-by: dependabot[bot] <support@github.com>

Bumps [axe-core](https://github.com/dequelabs/axe-core) from 4.1.3 to 4.1.4.
- [Release notes](https://github.com/dequelabs/axe-core/releases)
- [Changelog](https://github.com/dequelabs/axe-core/blob/v4.1.4/CHANGELOG.md)
- [Commits](https://github.com/dequelabs/axe-core/compare/v4.1.3...v4.1.4)
Signed-off-by: dependabot[bot] <support@github.com>

Bumps [@babel/core](https://github.com/babel/babel/tree/HEAD/packages/babel-core) from 7.13.13 to 7.13.14.
- [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/v7.13.14/packages/babel-core)
Signed-off-by: dependabot[bot] <support@github.com>

Karam expects the config to be of type `Config`. This can be done by calling the karma.config.parseConfig method which creates a Config object that can be passed to karma.Server()

Bumps [karma](https://github.com/karma-runner/karma) from 6.3.1 to 6.3.2.
- [Release notes](https://github.com/karma-runner/karma/releases)
- [Changelog](https://github.com/karma-runner/karma/blob/master/CHANGELOG.md)
- [Commits](https://github.com/karma-runner/karma/compare/v6.3.1...v6.3.2)
Signed-off-by: dependabot[bot] <support@github.com>

By nulling the `annotations` config var, the direct link fragment no longer affects annotations shown in the notebook.

Add back horizontal-rhythm util styles, but use a different alignment
technique for a child element to assure that timestamps align right in
annotation cards.

Remove an unneeded horizontal-rhythm mixin from AnnotationHeader. Fixes
a regression in which the timestamps were not appearing right-aligned
in the header of annotation cards.

* Move logic for adding a new, unsaved page note to AnnotationsService
* Render new-note button as a `LabeledButton` within `SelectionTabs`
* Remove `NewNoteBtn` component

To apply theming from settings, we need to be able to set inline styles
on buttons.

Use a simpler mixin for Notebook's "inner" container: we don't need
all the stuff in `panel`, `card-frame` suffices. This eliminates the
need to override a vertical rhythm rule.