Bump whatwg-fetch from 3.0.0 to 3.1.0

Make text-color SASS variable names match conventions

- Adjust a few related mixins
- Adjust tests; make them less brittle on CSS classes
- Fix arrow alignment for narrow viewports

Fix layout of `AnnotationPublishControl` for Safari

* Add a wrapper element around the `Menu` component and apply styles
  to make sure it stretches/fills vertical space in parent
* Add utility class for small icon styling

Fixes #2302

Bumps [eslint-plugin-react-hooks](https://github.com/facebook/react/tree/HEAD/packages/eslint-plugin-react-hooks) from 4.0.4 to 4.0.5.
- [Release notes](https://github.com/facebook/react/releases)
- [Changelog](https://github.com/facebook/react/blob/master/CHANGELOG.md)
- [Commits](https://github.com/facebook/react/commits/HEAD/packages/eslint-plugin-react-hooks)
Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Bump puppeteer from 4.0.1 to 5.0.0

Bump preact from 10.4.4 to 10.4.5

Bump through2 from 4.0.1 to 4.0.2

Bump @sentry/browser from 5.18.1 to 5.19.0

Bump typescript from 3.9.5 to 3.9.6

Enable type checking for src/sidebar/components, but exclude all the files that have errors

Bumps [@babel/preset-react](https://github.com/babel/babel/tree/HEAD/packages/babel-preset-react) from 7.10.1 to 7.10.4.
- [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/v7.10.4/packages/babel-preset-react)
Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Bumps [eslint](https://github.com/eslint/eslint) from 7.3.1 to 7.4.0.
- [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/v7.3.1...v7.4.0)
Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Bumps [@babel/core](https://github.com/babel/babel/tree/HEAD/packages/babel-core) from 7.10.3 to 7.10.4.
- [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/v7.10.4/packages/babel-core)
Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Bumps [puppeteer](https://github.com/puppeteer/puppeteer) from 4.0.1 to 5.0.0.
- [Release notes](https://github.com/puppeteer/puppeteer/releases)
- [Commits](https://github.com/puppeteer/puppeteer/compare/v4.0.1...v5.0.0)
Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Bumps [typescript](https://github.com/Microsoft/TypeScript) from 3.9.5 to 3.9.6.
- [Release notes](https://github.com/Microsoft/TypeScript/releases)
- [Commits](https://github.com/Microsoft/TypeScript/commits)
Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Bumps [through2](https://github.com/rvagg/through2) from 4.0.1 to 4.0.2.
- [Release notes](https://github.com/rvagg/through2/releases)
- [Commits](https://github.com/rvagg/through2/compare/v4.0.1...v4.0.2)
Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Bumps [whatwg-fetch](https://github.com/github/fetch) from 3.0.0 to 3.1.0.
- [Release notes](https://github.com/github/fetch/releases)
- [Commits](https://github.com/github/fetch/compare/v3.0.0...v3.1.0)
Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Bumps [preact](https://github.com/preactjs/preact) from 10.4.4 to 10.4.5.
- [Release notes](https://github.com/preactjs/preact/releases)
- [Commits](https://github.com/preactjs/preact/compare/10.4.4...10.4.5)
Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Bumps [@sentry/browser](https://github.com/getsentry/sentry-javascript) from 5.18.1 to 5.19.0.
- [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/5.18.1...5.19.0)
Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Send notifications to Slack about client deployment events

These files typecheck without any changes required

Enable typechecking for the src/sidebar/components directory, but add
all files in that directory to an exclusion list of files which are not
checked. As errors are resolved, they can be removed from that list.
This gives us a "burndown" list that we can work our way through.

Enable typechecking for sidebar/store/modules

Disable `_separate_replies` for annotation loading in sidebar (behind feature flag)

Typecheck UI components in src/annotator/components

- Add JSDoc for the `actionTypes` function. This uses an advanced
  TS feature called "mapped types" [1] to specify that the result is an
  object with the same keys as the input object, but where the values
  are strings rather than functions.

  Going forwards there are likely better ways to replace `actionTypes`.
  The original purpose was to make sure that the `type` field of each action
  object matches up with a key of the `updates` object.

- Fix various existing JSDoc errors
- Add imports for the existing `Group` and `Annotation` references
- Add missing `group` property to `Annotation` type

[1] https://www.typescriptlang.org/docs/handbook/advanced-types.html#mapped-types
    (See in particular the `in keyof T` mentions).

When associated feature flag is set, `_separate_replies` will be set
to `false` when loading annotations in the sidebar.

This follows the same pattern that was introduced for `SvgIcon` in
`propTypes` declarations are kept around for use at runtime by other
code which is not yet typechecked.

An issue that I encountered is that TS doesn't know about the custom
HTML element types we use. For the moment I have ignored these with
`@ts-ignore`, although I believe it should be possible to teach it.

Typecheck SvgIcon

 - Remove a param comment that duplicates information in the type
   definition
 - Add a note about a defensive null-check

Adjust the scale of layout spacing

Refactor annotation publish control styling

Typecheck `shared/components/svg-icon.js`. This enables edit-time rather than
runtime detection of incorrect usage, as well as enabling UI component
props to reference types (eg. API objects) defined elsewhere with JSDoc.

Props are currently declared with both JSDoc and via
`SvgIcon.propTypes`. The intent is that the JSDoc is the canonical
definition, but `SvgIcon.propTypes` is still useful to catch incorrect
usage from other parts of the code which are currently not typechecked.

Typecheck src/sidebar/services