Replace `share-annotation-dialog` with preact `AnnotationShareControl`

Add preact component for sharing a single annotation. Replace use of
`share-annotation-dialog` within the `annotation` component with this
new component.

Bump @sentry/browser from 5.9.0 to 5.9.1

Bump autoprefixer from 9.7.1 to 9.7.2

Bump sass from 1.23.6 to 1.23.7

Bump scroll-into-view from 1.12.2 to 1.12.3

Bumps [autoprefixer](https://github.com/postcss/autoprefixer) from 9.7.1 to 9.7.2.
- [Release notes](https://github.com/postcss/autoprefixer/releases)
- [Changelog](https://github.com/postcss/autoprefixer/blob/master/CHANGELOG.md)
- [Commits](https://github.com/postcss/autoprefixer/compare/9.7.1...9.7.2)
Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Bump angular-mocks from 1.7.8 to 1.7.9

Bump postcss from 7.0.21 to 7.0.23

Bumps [angular-mocks](https://github.com/angular/angular.js) from 1.7.8 to 1.7.9.
- [Release notes](https://github.com/angular/angular.js/releases)
- [Changelog](https://github.com/angular/angular.js/blob/master/CHANGELOG.md)
- [Commits](https://github.com/angular/angular.js/compare/v1.7.8...v1.7.9)
Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Bump angular-route from 1.7.8 to 1.7.9

Bumps [postcss](https://github.com/postcss/postcss) from 7.0.21 to 7.0.23.
- [Release notes](https://github.com/postcss/postcss/releases)
- [Changelog](https://github.com/postcss/postcss/blob/master/CHANGELOG.md)
- [Commits](https://github.com/postcss/postcss/compare/7.0.21...7.0.23)
Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Merge pull request #1534 from hypothesis/dependabot/npm_and_yarn/karma-coverage-istanbul-reporter-2.1.1

Bump karma-coverage-istanbul-reporter from 2.1.0 to 2.1.1

Bumps [@babel/preset-env](https://github.com/babel/babel) from 7.7.1 to 7.7.4.
- [Release notes](https://github.com/babel/babel/releases)
- [Changelog](https://github.com/babel/babel/blob/master/CHANGELOG.md)
- [Commits](https://github.com/babel/babel/compare/v7.7.1...v7.7.4)
Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Bumps [eslint](https://github.com/eslint/eslint) from 6.6.0 to 6.7.1.
- [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/v6.6.0...v6.7.1)
Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Bumps [aws-sdk](https://github.com/aws/aws-sdk-js) from 2.573.0 to 2.578.0.
- [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/v2.573.0...v2.578.0)
Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Bumps [karma-coverage-istanbul-reporter](https://github.com/mattlewis92/karma-coverage-istanbul-reporter) from 2.1.0 to 2.1.1.
- [Release notes](https://github.com/mattlewis92/karma-coverage-istanbul-reporter/releases)
- [Changelog](https://github.com/mattlewis92/karma-coverage-istanbul-reporter/blob/master/CHANGELOG.md)
- [Commits](https://github.com/mattlewis92/karma-coverage-istanbul-reporter/compare/v2.1.0...v2.1.1)
Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Bumps [angular-route](https://github.com/angular/angular.js) from 1.7.8 to 1.7.9.
- [Release notes](https://github.com/angular/angular.js/releases)
- [Changelog](https://github.com/angular/angular.js/blob/master/CHANGELOG.md)
- [Commits](https://github.com/angular/angular.js/compare/v1.7.8...v1.7.9)
Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Bumps [scroll-into-view](https://github.com/KoryNunn/scroll-into-view) from 1.12.2 to 1.12.3.
- [Release notes](https://github.com/KoryNunn/scroll-into-view/releases)
- [Changelog](https://github.com/KoryNunn/scroll-into-view/blob/master/CHANGELOG.md)
- [Commits](https://github.com/KoryNunn/scroll-into-view/commits)
Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Bumps [@sentry/browser](https://github.com/getsentry/sentry-javascript) from 5.9.0 to 5.9.1.
- [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/5.9.0...5.9.1)
Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Bumps [sass](https://github.com/sass/dart-sass) from 1.23.6 to 1.23.7.
- [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/1.23.6...1.23.7)
Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Bumps [@babel/core](https://github.com/babel/babel) from 7.7.2 to 7.7.4.
- [Release notes](https://github.com/babel/babel/releases)
- [Changelog](https://github.com/babel/babel/blob/master/CHANGELOG.md)
- [Commits](https://github.com/babel/babel/compare/v7.7.2...v7.7.4)
Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Bumps [@babel/preset-react](https://github.com/babel/babel) from 7.7.0 to 7.7.4.
- [Release notes](https://github.com/babel/babel/releases)
- [Changelog](https://github.com/babel/babel/blob/master/CHANGELOG.md)
- [Commits](https://github.com/babel/babel/compare/v7.7.0...v7.7.4)
Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Rename the username to userid in selection module

The username was really the userid and was named incorrectly.
Still allow username in the config to work in the meantime until its depreciated in LMS

Convert SASS files to SASS modules

Prepare SASS files for transition to SASS modules

Update icons in `MarkdownEditor`; add Help Link

Merge in recent changes to app styles.

Extract `ShareLinks` component