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`.

This covers the functionality related to the submenu for group list items.

Conditionally rendered items create boolean `false` entries in the
`children` prop when the condition is false.

To indicate that there are no special restrictions on the `children`
prop here beyond them being some kind of renderable content, I've opted
for the `any` prop type.

Avoid showing a focus ring on the item when activating it via
touch/mouse for consistency with how other tab-reachable parts of the
menu and top bar work.

Group names are user supplied and can be up to 25 chars, so allow more
space for this.

This can be used to set a custom minimum width for a particular menu for
example.

The name of the "groups" service is slightly ambiguous in this context.
We can't rename the prop because service dependencies are resolved by
name and the service is called "groups" when registered with Angular.

Convert portions of login-control component to (preact) UserMenu component

The URL fragment syntax for direct links only supports either an
annotation or a group, the client's JSON configuration however currently allows
both an annotation and a group to be specified. If that happens, the
client goes to the group containing the direct-linked annotation, but
will still add the direct-linked group to the groups list.

Open sidebar when highlighting while logged-out

Previously the error message about not being able to create
annotations when logged out only mentioned annotations but,
technically you cannot create highlights either. Change the
error message to include highlights as well.

When the user creates a highlight while logged out, they appear to
work however, they silently do not get saved. An error message
does pop up in the sidebar informing them they cannot create annotations
when not logged in but they don't see it because the sidebar does not
open when creating a highlight. This makes the error message more
apparent to the user by popping open the sidebar.

Bump prettier from 1.17.1 to 1.18.2

Bump raven-js from 3.27.1 to 3.27.2