I evaluated popular npm packages for this purpose (eg. [1]) but encountered
issues where they were not transpiled for use in older browsers or
included workarounds for browsers we no longer support (eg. IE 9).

If we do decide to use an existing package in future, we can keep this
utility module as a wrapper around it.

[1] https://github.com/sindresorhus/copy-text-to-clipboard

Update group menu styles

This enables consumers to use `&&` or `||` conditionals to compute the
`icon` prop.

Convert `<search-input>` component to Preact

 - {show, hide} => {renders, doesn't render} to clarify that we're
   checking whether an element is rendered at all, as opposed to merely
   visually hidden
 - Replace ambiguous GitHub issue reference with URL

This makes it easier to see when a submenu item is hovered.

 - Use the string "blank" instead of `null` as a more explicit indicator
   that a menu item should show a blank space for an icon
 - Rename two variables to indicate their boolean-ness

The icon is from the Hypothicons set at https://hypothicons.netlify.com

Following a design review, adjust the styling of menus and in particular the
groups menu to better match the mocks [1] and create better separation between
different elements.

- Add a 10px margin below section headers
- Add a subtle border at bottom of expanded submenus
- Remove red hover color for menu items
- Make submenu items slightly lighter and darken them on hover
- Reduce font size to match top bar and reduce font weight for submenu items
- Increase submenu toggle caret size slightly (10 => 12px) and darken
  the caret on hover, consistent with the effect when submenu items are
  hovered.
- Avoid hyphenating messages in the footer of group list submenus

[1] https://sketch.cloud/s/D0OMk/a/EbnxQA/play

Bump focus-visible from 4.1.5 to 5.0.0

Bump @octokit/rest from 16.28.0 to 16.28.2

 - Remove `@import` commands which duplicated SASS imports elsewhere in
   the bundle
 - Remove `:focus` selector which had no effect
 - Remove an unnecessary `@at-root` block which was used to contain a
   variable that was only used in one place and replace that usage with
   a constant instead

 - Rename `simple-search.scss` and the CSS classes it defines to match
   the name of the module which defines the component structure and
   logic
 - Remove reference to `simple-search-inactive` CSS class which did not
   exist

Merge pull request #1176 from hypothesis/dependabot/npm_and_yarn/babel-plugin-transform-async-to-promises-0.8.12

Bump babel-plugin-transform-async-to-promises from 0.8.11 to 0.8.12

Bump enzyme-adapter-preact-pure from 1.13.4 to 2.0.0

This test happened to pass before, but failed after an adapter upgrade.
All external state changes should be wrapped in `act` to flush state
updates and effects and followed by `wrapper.update` to update the
Enzyme adapter.

Bumps [@octokit/rest](https://github.com/octokit/rest.js) from 16.28.0 to 16.28.2.
- [Release notes](https://github.com/octokit/rest.js/releases)
- [Commits](https://github.com/octokit/rest.js/compare/v16.28.0...v16.28.2)
Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Bumps [enzyme-adapter-preact-pure](https://github.com/preactjs/enzyme-adapter-preact-pure) from 1.13.4 to 2.0.0.
- [Release notes](https://github.com/preactjs/enzyme-adapter-preact-pure/releases)
- [Changelog](https://github.com/preactjs/enzyme-adapter-preact-pure/blob/master/CHANGELOG.md)
- [Commits](https://github.com/preactjs/enzyme-adapter-preact-pure/compare/v1.13.4...v2.0.0)
Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Bumps [babel-plugin-transform-async-to-promises](https://github.com/rpetrich/babel-plugin-transform-async-to-promises) from 0.8.11 to 0.8.12.
- [Release notes](https://github.com/rpetrich/babel-plugin-transform-async-to-promises/releases)
- [Commits](https://github.com/rpetrich/babel-plugin-transform-async-to-promises/compare/v0.8.11...v0.8.12)
Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Bumps [focus-visible](https://github.com/WICG/focus-visible) from 4.1.5 to 5.0.0.
- [Release notes](https://github.com/WICG/focus-visible/releases)
- [Commits](https://github.com/WICG/focus-visible/compare/v4.1.5...v5.0.0)
Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Convert loading spinner to Preact

Remove passing of search

Previously a search object was built inside the hypothesis-app
component and passed down to its child components. Now, just use
the store.getState().filterQuery directly. This avoids unnecessarily
passing things between components and a layer of indirection between
the search object and the value in the store. Rename searchQuery to
filterQuery.

Simplify groups service `load` method using async/await

As per previous commit, it is currently possible for client
configuration to specify both an annotation to focus and an additional
group to include.

Move sidebar-content funcs to search-status-bar

Convert `help-link` component to preact

- filterMatchCount
- areAllAnnotationsVisible
- Remove passing of total-count as it's not used.

- Add tests

Replace help icon with lighter variant

- Add `height` rule to `top-bar__btn` to help with alignment

Implement new groups menu design built on groups menu

Also mock the `MenuItem` component manually so that any problems with
that component won't cause a cascade of failures in `GroupListItem`.