Convert ‘Log in’ and ‘Sign up’ links to `Button` components

Part of #1727

Highlights a11y (2/2) - Make highlights "visible" to screen readers

Use CSS `::before` and `::after` to add "comment start" and "commend
end" notices around highlighted text which screen readers will read but
which are not visible.

This pattern follows the example of how highlights are presented in
Google Docs and also a suggestion in a blog post from the Paciello
Group.

This will get quite audibly "noisy" if there are a lot of overlapping
highlights, but I think it is better than not having the highlights be
visible to screen reader users at all.

Highlight a11y (1/2) - Rename highlights CSS styles and move to separate module

We're renaming CSS classes to have a `hypothesis-` prefix to make it
more obvious what they are associated with, so update the selector
accordingly.

 - Remove the vestigial "annotator-" prefix for the hypothesis highlight
   CSS rules and replace with "hypothesis-".

 - Move the highlights styles to a separate module for consistency with
   the sidebar styles, where each component's styles goes in its own
   module and also to simplify the entry point (annotator.scss) module

Fix eslint issues in HelpPanel component

Decouple `wrapReactComponent` from Angular `$injector`

Pass the service container directly to `wrapReactComponent` instead of
looking up services via Angular's `$injector` service.

This removes the need to register services with Angular if only other
services or Preact components use them. This will enable us to
incrementally remove these service registrations as the migration
continues.

As a starting point, remove the "tags" service registration, as all the
UI components and services that use it have been migrated.

Add missing effect dependencies in StreamSearchInput

Remove unnecessary registration of several classes / functions with Angular

Add `save` method to `AnnotationsService`; use it in `AnnotationOmega`

Also add polyfill for `Promise.prototype.finally`

This fixes an issue, and corresponding warning in tests, where an effect
would unnecessarily run on every render.

See https://hypothes-is.slack.com/archives/C1M8NH76X/p1581517940185900

- <a> tags without real href attributes should be converted to buttons.
- Did not use our button component in this instance because we don’t have control over the icon position relative to the text.

Bump axe-core from 3.4.1 to 3.4.2

Bump codecov from 3.6.4 to 3.6.5

Bump puppeteer from 2.1.0 to 2.1.1

Bump @sentry/browser from 5.11.2 to 5.12.1

Bump preact from 10.2.1 to 10.3.1

Bumps [aws-sdk](https://github.com/aws/aws-sdk-js) from 2.610.0 to 2.614.0.
- [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/v2.610.0...v2.614.0)
Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Bumps [@octokit/rest](https://github.com/octokit/rest.js) from 16.43.0 to 16.43.1.
- [Release notes](https://github.com/octokit/rest.js/releases)
- [Commits](https://github.com/octokit/rest.js/compare/v16.43.0...v16.43.1)
Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Bumps [eslint-plugin-react](https://github.com/yannickcr/eslint-plugin-react) from 7.18.0 to 7.18.3.
- [Release notes](https://github.com/yannickcr/eslint-plugin-react/releases)
- [Changelog](https://github.com/yannickcr/eslint-plugin-react/blob/master/CHANGELOG.md)
- [Commits](https://github.com/yannickcr/eslint-plugin-react/compare/v7.18.0...v7.18.3)
Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Bumps [@sentry/browser](https://github.com/getsentry/sentry-javascript) from 5.11.2 to 5.12.1.
- [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/5.11.2...5.12.1)
Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Bumps [puppeteer](https://github.com/puppeteer/puppeteer) from 2.1.0 to 2.1.1.
- [Release notes](https://github.com/puppeteer/puppeteer/releases)
- [Commits](https://github.com/puppeteer/puppeteer/compare/v2.1.0...v2.1.1)
Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Bumps [codecov](https://github.com/codecov/codecov-node) from 3.6.4 to 3.6.5.
- [Release notes](https://github.com/codecov/codecov-node/releases)
- [Commits](https://github.com/codecov/codecov-node/commits)
Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Bumps [axe-core](https://github.com/dequelabs/axe-core) from 3.4.1 to 3.4.2.
- [Release notes](https://github.com/dequelabs/axe-core/releases)
- [Changelog](https://github.com/dequelabs/axe-core/blob/v3.4.2/CHANGELOG.md)
- [Commits](https://github.com/dequelabs/axe-core/compare/v3.4.1...v3.4.2)
Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Bumps [preact](https://github.com/preactjs/preact) from 10.2.1 to 10.3.1.
- [Release notes](https://github.com/preactjs/preact/releases)
- [Commits](https://github.com/preactjs/preact/compare/10.2.1...10.3.1)
Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

 - Stop using dependency injection to mock `OAuthClient`, `Discovery`
   `VirtualThreadList` and `serviceConfig` in tests. Use our modern mocking
   tools instead. This removes unnecessary indirection and runtime
   overhead.

 - Remove unused `random` and `time` values from the dependency
   injection container. The code that used to rely on these has since
   been rewritten to import the modules directly.

Add `disabled` prop to the Button component

Fix a11y lint issues in menu.js

No other code referenced this filter.

Services that are only used by other services no longer need to be
registered with Angular, since the new dependency injection container
handles wiring them up.

Implement container to replace AngularJS's dependency injector for services (v2)

Previously a heuristic based on function naming was used to determine
whether `Injector` should construct objects with `new` or not. This is
brittle because compiler transforms may alter function names (eg. terser
removes them by default).

This commit re-works the API so that the caller explicitly indicates how
the object should be created (the "provider" to use). As a convenience
if a function is passed it is assumed to be a class.

```
// Register a class.
register("anObject", SomeClass);
register("anObject", { class: SomeClass });

// Register a factory.
register("anObject", { factory: makeMeAnObject });

// Register a plain value.
register("anObject", { value: "foobar" });
```

This reverts commit ec63961a, reversing
changes made to e0f8835c.