This is part of replacing all uses of AngularJS promises with native
promises.

Part of #972

Move API activity state to store

Replace $http with fetch in api-routes service

Call `store.apiRequestStarted` and `store.apiRequestFinished` methods
when API requests start and finish. This causes the loading spinner to
correctly indicate whether API requests are in progress.

Reflect the loading state of the app reported by `store.isLoading()` in
the bar at the top of the UI, instead of querying
`$http.pendingRequests`.

This is part of the migration the Hypothesis API client away from
AngularJS's $http to `fetch`.

As part of the move away from AngularJS, we need to replace the current
logic in the `<search-input>` component for determining whether any
activity is happening in the app that should result in a loading
indicator being shown.

This commit adds a module to the store that holds activity-related state
which can be used when rendering the UI.

As part of the migration away from AngularJS, replace use of the `$http`
service with `fetch` when fetching API route information from the `/api/`
route.

This is part of #974.

Replace $http with fetch in OAuthClient

Fix Google Analytics event reporting

Fix a race condition where events would not be reported if the analytics
service was instantiated before Google Analytics had fully loaded.

The main interface to Google Analytics, `window.ga`, is initially a
simple function which just records commands in a buffer. When
analytics.js loads it sends the buffered events and replaces `window.ga`
with a function that sends new events immediately. The analytics service
captured the value of `window.ga` at the time it was instantiated and did
not use the replacement after GA loaded. As a result tracked events were
just stored in a buffer and never send to GA.

Fix this by removing the `GoogleAnalytics` wrapper class and always invoking
the _current_ `window.ga` function.

Also update the documentation of the service's methods and add pointers to
relevant Google Analytics docs.

Fixes #976

Remove angulartics dependency

Replace angular-sanitize with DOMPurify

Bump eslint from 5.15.0 to 5.15.1

Bump autoprefixer from 9.4.9 to 9.4.10

Bump @octokit/rest from 16.16.3 to 16.17.0

Bumps [autoprefixer](https://github.com/postcss/autoprefixer) from 9.4.9 to 9.4.10.
- [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/9.4.9...9.4.10)
Signed-off-by: dependabot[bot] <support@dependabot.com>

Bumps [eslint](https://github.com/eslint/eslint) from 5.15.0 to 5.15.1.
- [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/v5.15.0...v5.15.1)
Signed-off-by: dependabot[bot] <support@dependabot.com>

Bumps [@octokit/rest](https://github.com/octokit/rest.js) from 16.16.3 to 16.17.0.
- [Release notes](https://github.com/octokit/rest.js/releases)
- [Commits](https://github.com/octokit/rest.js/compare/v16.16.3...v16.17.0)
Signed-off-by: dependabot[bot] <support@dependabot.com>

Add show section logic

As part of the migration away from AngularJS, replace `$http` with
`fetch` in the OAuthClient class which handles interactions with h's
OAuth endpoints.

For testing use the fetch-mock library that is already used in h's
frontend tests. The current version (v7) has dependencies that are
written in ES6 and not transpiled, and so don't work in PhantomJS [1]. As a
workaround, use v6 of the library for the time being.

This is part of #974.

[1] We _do_ transpile our own code from ES6 -> ES5 but that transform is
    not applied to dependencies.

Also improve the documentation on how to add a new polyfill in future.

As part of the migration away from AngularJS, replace Angulartics with
direct usage of the Google Analytics client.

Since we only use a single analytics provider (Google Analytics) and
only basic event tracking functionality in a single-route application,
its easiest just to replace the code with direct calls to the
analytics.js API.

See https://developers.google.com/analytics/devguides/collection/analyticsjs/events

Fixes #976

In preparation for the move away from AngularJS, replace
angular-sanitize with the DOMPurify library, which is a modern and
widely used HTML sanitization library with no framework dependency.

The sanitization logic is now encapsulated fully within the
`render-markdown` module which no longer takes a sanitization function
as an argument. That argument used to be necessary because
the angular-sanitize function had to be obtained via Angular's
dependency injection. DOMPurify can just be required as a module inside
render-markdown.js.

One improvement that is possible with DOMPurify but not done here is to
generate sanitized DOM nodes directly instead of having showdown
generate HTML, which is then parsed to DOM and sanitized, then converted
back to HTML and finally converted back to DOM by Angular.

Fixes #975

- isFeatureFlagEnabled will be used to feature flag the groups-list
  template.
- When the community_groups feature flag is enabled, only show the
  groups drop down menu if there is more than one group present.
  This varies slightly from the current behavior where this only
  happens if it is a thirdparty account.
- Fix the group const names to follow js cammel case convention and
  use full groups rather than recreating them every time.

Only build client before publishing, not when running `yarn install`

Bump sinon from 7.2.6 to 7.2.7

Bump eslint from 5.14.1 to 5.15.0

Bump @octokit/rest from 16.16.2 to 16.16.3

Bumps [sinon](https://github.com/sinonjs/sinon) from 7.2.6 to 7.2.7.
- [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/v7.2.6...v7.2.7)
Signed-off-by: dependabot[bot] <support@dependabot.com>

Bump sinon from 7.2.4 to 7.2.6

Bump through2 from 3.0.0 to 3.0.1

Bump karma from 4.0.0 to 4.0.1

Bumps [sinon](https://github.com/sinonjs/sinon) from 7.2.4 to 7.2.6.
- [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/v7.2.4...v7.2.6)
Signed-off-by: dependabot[bot] <support@dependabot.com>

Bumps [eslint](https://github.com/eslint/eslint) from 5.14.1 to 5.15.0.
- [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/v5.14.1...v5.15.0)
Signed-off-by: dependabot[bot] <support@dependabot.com>

Bumps [karma](https://github.com/karma-runner/karma) from 4.0.0 to 4.0.1.
- [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/v4.0.0...v4.0.1)
Signed-off-by: dependabot[bot] <support@dependabot.com>

Bumps [@octokit/rest](https://github.com/octokit/rest.js) from 16.16.2 to 16.16.3.
- [Release notes](https://github.com/octokit/rest.js/releases)
- [Commits](https://github.com/octokit/rest.js/compare/v16.16.2...v16.16.3)
Signed-off-by: dependabot[bot] <support@dependabot.com>

Bumps [through2](https://github.com/rvagg/through2) from 3.0.0 to 3.0.1.
- [Release notes](https://github.com/rvagg/through2/releases)
- [Commits](https://github.com/rvagg/through2/compare/v3.0.0...v3.0.1)
Signed-off-by: dependabot[bot] <support@dependabot.com>