Unloading the client (eg. by deactivating the Hypothesis extension) does
not currently work properly in VitalSource ebooks or other scenarios involving
iframes. Add an "Unload client" toggle button in the VS test page at
http://localhost:3000/document/vitalsource-epub to help with testing
this.

The code for this button has been extracted from the dev server's home page into
a shared `controls.js` module.

In the process I removed the comments about Babel from util.js/index.js as these
are much less relevant now, and instead added some notes at the top of
dev-server/static/scripts/util.js about why that file is not an ES module.

Avoid the temporary URL navigation done by VitalSource tests from affecting
other tests by pausing in `afterEach` until the async `history.back()` operation
has completed. Note this API doesn't return a promise. Waiting for `popstate` is
how MDN recommends waiting.

Fixes #5004

Bumps [typescript](https://github.com/Microsoft/TypeScript) from 4.8.4 to 4.9.3.
- [Release notes](https://github.com/Microsoft/TypeScript/releases)
- [Commits](https://github.com/Microsoft/TypeScript/compare/v4.8.4...v4.9.3)

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This commit started out as a fix for a typecheck error in TypeScript 4.9.3 in
`search-filter.js` that led to a discovery of missing tests for handling of
empty inputs and redundant checks for empty inputs in the implementation.

Add tests for empty queries and clean up the implementation.

Bumps [sinon](https://github.com/sinonjs/sinon) from 14.0.1 to 14.0.2.
- [Release notes](https://github.com/sinonjs/sinon/releases)
- [Changelog](https://github.com/sinonjs/sinon/blob/main/docs/changelog.md)
- [Commits](https://github.com/sinonjs/sinon/compare/v14.0.1...v14.0.2)

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Bumps [preact](https://github.com/preactjs/preact) from 10.11.2 to 10.11.3.
- [Release notes](https://github.com/preactjs/preact/releases)
- [Commits](https://github.com/preactjs/preact/compare/10.11.2...10.11.3)

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Bumps [eslint](https://github.com/eslint/eslint) from 8.25.0 to 8.28.0.
- [Release notes](https://github.com/eslint/eslint/releases)
- [Changelog](https://github.com/eslint/eslint/blob/main/CHANGELOG.md)
- [Commits](https://github.com/eslint/eslint/compare/v8.25.0...v8.28.0)

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Bumps [axe-core](https://github.com/dequelabs/axe-core) from 4.5.1 to 4.5.2.
- [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/v4.5.1...v4.5.2)

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Bumps [aws-sdk](https://github.com/aws/aws-sdk-js) from 2.1253.0 to 2.1258.0.
- [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/v2.1253.0...v2.1258.0)

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Bumps [@typescript-eslint/parser](https://github.com/typescript-eslint/typescript-eslint/tree/HEAD/packages/parser) from 5.42.0 to 5.43.0.
- [Release notes](https://github.com/typescript-eslint/typescript-eslint/releases)
- [Changelog](https://github.com/typescript-eslint/typescript-eslint/blob/main/packages/parser/CHANGELOG.md)
- [Commits](https://github.com/typescript-eslint/typescript-eslint/commits/v5.43.0/packages/parser)

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Bumps [@sentry/cli](https://github.com/getsentry/sentry-cli) from 2.8.1 to 2.9.0.
- [Release notes](https://github.com/getsentry/sentry-cli/releases)
- [Changelog](https://github.com/getsentry/sentry-cli/blob/master/CHANGELOG.md)
- [Commits](https://github.com/getsentry/sentry-cli/compare/2.8.1...2.9.0)

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Bumps [@sentry/browser](https://github.com/getsentry/sentry-javascript) from 7.19.0 to 7.20.0.
- [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/7.19.0...7.20.0)

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Increase clarity of highlights SASS by documenting where highlight
colors come from and renaming the argument for the `clusterHighlightStyles`
mixin. Remove transitions for now until they can be tuned.

Set explicit second and third colors to use for nested highlights in
highlight clusters, instead of using `mix-blend-mode: multiply`.

This will allow us to style drawn SVG highlights for PDFS, as transparency
or blending is not feasible for those.

Reorganize CSS and CSS variables a bit to prepare for next steps.

Prepare for some upcoming changes to this module.

When annotations are loaded into the sidebar, they are not displayed in the
"Annotations" tab immediately. Instead the client waits until the guest reports
that the annotation was successfully anchored, or a timeout expires. This is to
avoid annotations briefly appearing in the Annotations tab and then "jumping" to
the Orphans tab a moment later if they fail to anchor.

For annotations in document segments (eg. EPUB chapters) other than the one
currently loaded in a guest frame, the annotation will never anchor in the
guest, and so the annotation did not appear in the sidebar until the anchoring
timeout expired. The result was that current-chapter annotations appeared
quickly, and other-chapter annotations appeared in the sidebar several hundred
ms later.

This commit improves the experience by optimisitically assuming annotations
in other chapters will anchor when the user navigates to those chapters, and
immediately marking them as "anchored" in the store. If they fail to anchor
when the user navigates to the chapter, then the status will be updated and
the annotation will be marked as an orphan at that point.

Visual change: CopyIcon is now proportional with text in button (icon
is smaller)

Visual change: Link hover is `brand` instead of `brand-dark` to match
conventional color combinations.

Visual change: font in button to expand and collapse excerpt is now
semi-bold, which matches all of our other buttons.

Simplify internal components (remove `HeaderRow` local component).

Visual change: hover on expand-replies is `brand` instead of
`brand-dark`—this is a standard hover color for a light-colored link.

Ensure that hovered annotations are cleared in the store when `null` is
passed to `FrameSyncService.hoverAnnotations`.

Following https://github.com/hypothesis/client/pull/4962, we can now identify
annotations that should be scrolled to/focused after they anchor by their tag
rather than ID, since the annotation in the sidebar's store persists across the
chapter navigation.