Improve readability of nested highlights in PDFs

- Tab will add the first suggestion in the autocomplete list if the list is not empty and `Tab` is pressed without any suggestion being selected.
- Tab can act as `Enter` or `,` and add a selected tag from a list when pressed.

Allow `groups` filter to resolve from an RCP ancestor frame
- If the groups array exists at load time, leave it in place.
- If the groups array value is equal to '$rcp:requestGroups' then fetch that value with a second RCP request to the ancestor frame.

Remove annotation-mapper service and associated Angular events

Move coverage reporting from Travis to Jenkins

Bumps [aws-sdk](https://github.com/aws/aws-sdk-js) from 2.648.0 to 2.653.0.
- [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/v2.648.0...v2.653.0)
Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Move management of “isSaving” state for annotations into the store

Bump dom-node-iterator from 3.5.3 to 5.0.0

Bump focus-visible from 5.0.2 to 5.1.0

Bump axe-core from 3.5.2 to 3.5.3

Bump dom-anchor-text-position from 4.0.0 to 5.0.0

Bump terser from 4.6.7 to 4.6.10

Bumps [prettier](https://github.com/prettier/prettier) from 2.0.2 to 2.0.4.
- [Release notes](https://github.com/prettier/prettier/releases)
- [Changelog](https://github.com/prettier/prettier/blob/master/CHANGELOG.md)
- [Commits](https://github.com/prettier/prettier/compare/2.0.2...2.0.4)
Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Bumps [terser](https://github.com/terser/terser) from 4.6.7 to 4.6.10.
- [Release notes](https://github.com/terser/terser/releases)
- [Changelog](https://github.com/terser/terser/blob/master/CHANGELOG.md)
- [Commits](https://github.com/terser/terser/compare/v4.6.7...v4.6.10)
Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Bumps [dom-anchor-text-position](https://github.com/tilgovi/dom-anchor-text-position) from 4.0.0 to 5.0.0.
- [Release notes](https://github.com/tilgovi/dom-anchor-text-position/releases)
- [Commits](https://github.com/tilgovi/dom-anchor-text-position/compare/v4.0.0...v5.0.0)
Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Bumps [axe-core](https://github.com/dequelabs/axe-core) from 3.5.2 to 3.5.3.
- [Release notes](https://github.com/dequelabs/axe-core/releases)
- [Changelog](https://github.com/dequelabs/axe-core/blob/develop/CHANGELOG.md)
- [Commits](https://github.com/dequelabs/axe-core/compare/v3.5.2...v3.5.3)
Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Bumps [focus-visible](https://github.com/WICG/focus-visible) from 5.0.2 to 5.1.0.
- [Release notes](https://github.com/WICG/focus-visible/releases)
- [Commits](https://github.com/WICG/focus-visible/compare/v5.0.2...v5.1.0)
Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Bumps [dom-node-iterator](https://github.com/tilgovi/dom-node-iterator) from 3.5.3 to 5.0.0.
- [Release notes](https://github.com/tilgovi/dom-node-iterator/releases)
- [Commits](https://github.com/tilgovi/dom-node-iterator/compare/v3.5.3...v5.0.0)
Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Jenkins is the primary CI system and the source of truth for test
status, so it makes sense to generate coverage reports here too.

This also paves the way for potentially replacing codecov for coverage
status reporting with an alternative system in future which produces
output that devs find easier to work with.

In PDFs, highlights are drawn in an otherwise-transparent text layer _on
top_ of a canvas which displays the text that the user sees. Therefore
highlights reduce the contrast of the text below and more than two
levels starts to make the text very difficult to read.

The ideal solution would be to draw the highlights below the text, but
that's not trivial.

As a simple step to improve the situation, make nested highlights that
are 3+ levels deep transparent. This limits the amount of contrast
reduction that overlapping highlights can cause.

In web pages, the highlights are drawn _behind_ the text, so contrast is
not reduced as much, but the same change is applied there for a
consistent experience and also because it is easier to implement.

Partially addresses:

 - https://github.com/hypothesis/client/issues/1995
 - https://github.com/hypothesis/client/issues/408

Replace `annotationMapper.loadAnnotations` with a direct call to
`store.addAnnotations`, since `loadAnnotations` is now just a trivial
wrapper around it.

Replace `annotationMapper.{deleteAnnotation, flagAnnotation}` with
`annotationsService.{delete, flag}`.

This is another step towards consolidating the logic for making
annotation-related API calls and updating the store into the annotations
service and removing the legacy annotationMapper service.

These events are now just indirection around a call to
`store.addAnnotations`.

Replace ANNOTATION_DELETED event with direct call to
`store.removeAnnotations`.

Nothing listened for this.

`$rootScope` was used to trigger an Angular digest cycle after
processing WebSocket messages. This is no longer necessary as WS
messages trigger store action dispatches and the store takes care of any
steps needed to update the UI.

Fix Hammer.JS error on web pages that use Require.JS

Add button to adder toolbar to show annotations for selection

Remove `onReplyCountClick` prop and use store method instead

Add a button to the adder toolbar to show the existing annotations that
relate to the selected text, along with a keyboard shortcut (the "s"
key) to trigger it. This provides a way to filter annotations in the
sidebar to those that correspond to a particular highlight or region of
text using only the keyboard.

Instead of an icon the "Show" toolbar button displays a badge whose
label is the number of annotations associated with the selection, as
that is more informative.

In implementing this, the CSS for the adder toolbar was refactored to
make the effects of several rules easier to follow and improve readability of
toolbar button labels:

 - Use of `!important` was removed. This used to be for the purpose of
   overriding any page styles which affected the adder. That issue no
   longer applies in most browsers due to the use of Shadow DOM to
   isolate the adder from the page's styles.

   This may cause a regression on some pages in older browsers which don't
   support Shadow DOM, if those pages' have generic CSS rules which
   style generic elements.

 - To make the label easier to read, the font size was slightly
   increased

Fix an error related to Hammer.JS on client startup on pages that define
a global variable called `define`, which is part of Require.JS. Hammer's UMD
bundle does not set `module.exports` in this case, so modules that import it
get an empty object back.

Fix the issue by making sure that any reference to `define` inside
bundles evaluates to undefined (assuming there is no local variable
within the module with that name).

This fixes an issue where clicking "Annotate" failed to open the sidebar
on BBC News articles (eg. https://www.bbc.co.uk/news/world-52144390).

Let `AnnotationHeader` call `store.setCollapsed` directly instead of
passing a callback down through several layers of components

Move the “isSaving” state management out of a UI component and into the
store via the `AnnotationsService.save` method.

Fix annotation and thread vertical rhythm and layout