Replace uses of `Button` in the Thread component and adjust
styling for stronger alignment in both desktop and touch interfaces.

Add a full novel as a test document for testing performance and
behaviors related to long PDF documents, such as re-anchoring when pages
are rendered and un-rendered while scrolling through the document.

We try to keep example PDFs small to avoid bloating the git repository, but
this one is on the larger side (~700KB) due to its length.

This PDF was produced by downloading the EPUB version of the novel [1]
from Project Gutenberg and then converting it to a PDF using Calibre [2]

[1] https://www.gutenberg.org/ebooks/64317
[2] https://calibre-ebook.com

The types for `SortBy` and `SortOrder` were swapped.

This matches how Prettier formats self-closing JSX tags and makes
expressions such as `<Widget expanded />` more readable.

 - Indent children by two spaces

 - Handle boolean props closer to how we normally set them in JSX by omitting
   them if false and including them without explicit values if true.
   This assumes that boolean props default to false. If there is a
   scenario in future where this is not the case, this behavior may need
   to be configurable.

 - Handle `bigint` numeric values. We have no use case for this, but
   TypeScript pointed out that it wasn't handled.

 - Add JSDoc comments

* Break out most private mixins into `_base`
* Provide `IconButton`, `LabeledButton`, `LinkButton` as public mixins
* Establish colors for all variants in `_config`
* Extend mixins to support sizes and more variants
* Update `TopBar` and `SearchInput`, as custom styling no longer
  necessary; remove those custom styles

Bumps [@sentry/browser](https://github.com/getsentry/sentry-javascript) from 6.2.3 to 6.2.5.
- [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/6.2.3...6.2.5)
Signed-off-by: dependabot[bot] <support@github.com>

Bumps [aws-sdk](https://github.com/aws/aws-sdk-js) from 2.874.0 to 2.880.0.
- [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/v2.874.0...v2.880.0)
Signed-off-by: dependabot[bot] <support@github.com>

Bumps [postcss](https://github.com/postcss/postcss) from 8.2.8 to 8.2.9.
- [Release notes](https://github.com/postcss/postcss/releases)
- [Changelog](https://github.com/postcss/postcss/blob/main/CHANGELOG.md)
- [Commits](https://github.com/postcss/postcss/compare/8.2.8...8.2.9)
Signed-off-by: dependabot[bot] <support@github.com>

Bumps [core-js](https://github.com/zloirock/core-js/tree/HEAD/packages/core-js) from 3.9.1 to 3.10.0.
- [Release notes](https://github.com/zloirock/core-js/releases)
- [Changelog](https://github.com/zloirock/core-js/blob/master/CHANGELOG.md)
- [Commits](https://github.com/zloirock/core-js/commits/v3.10.0/packages/core-js)
Signed-off-by: dependabot[bot] <support@github.com>

Bumps [classnames](https://github.com/JedWatson/classnames) from 2.2.6 to 2.3.1.
- [Release notes](https://github.com/JedWatson/classnames/releases)
- [Changelog](https://github.com/JedWatson/classnames/blob/master/HISTORY.md)
- [Commits](https://github.com/JedWatson/classnames/commits)
Signed-off-by: dependabot[bot] <support@github.com>

Bumps [sinon](https://github.com/sinonjs/sinon) from 9.2.4 to 10.0.0.
- [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/v9.2.4...v10.0.0)
Signed-off-by: dependabot[bot] <support@github.com>

Bumps [aws-sdk](https://github.com/aws/aws-sdk-js) from 2.874.0 to 2.879.0.
- [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/v2.874.0...v2.879.0)
Signed-off-by: dependabot[bot] <support@github.com>

Bumps [axe-core](https://github.com/dequelabs/axe-core) from 4.1.3 to 4.1.4.
- [Release notes](https://github.com/dequelabs/axe-core/releases)
- [Changelog](https://github.com/dequelabs/axe-core/blob/v4.1.4/CHANGELOG.md)
- [Commits](https://github.com/dequelabs/axe-core/compare/v4.1.3...v4.1.4)
Signed-off-by: dependabot[bot] <support@github.com>

Bumps [@babel/core](https://github.com/babel/babel/tree/HEAD/packages/babel-core) from 7.13.13 to 7.13.14.
- [Release notes](https://github.com/babel/babel/releases)
- [Changelog](https://github.com/babel/babel/blob/main/CHANGELOG.md)
- [Commits](https://github.com/babel/babel/commits/v7.13.14/packages/babel-core)
Signed-off-by: dependabot[bot] <support@github.com>

Karam expects the config to be of type `Config`. This can be done by calling the karma.config.parseConfig method which creates a Config object that can be passed to karma.Server()

Bumps [karma](https://github.com/karma-runner/karma) from 6.3.1 to 6.3.2.
- [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/v6.3.1...v6.3.2)
Signed-off-by: dependabot[bot] <support@github.com>

By nulling the `annotations` config var, the direct link fragment no longer affects annotations shown in the notebook.

Add back horizontal-rhythm util styles, but use a different alignment
technique for a child element to assure that timestamps align right in
annotation cards.

Remove an unneeded horizontal-rhythm mixin from AnnotationHeader. Fixes
a regression in which the timestamps were not appearing right-aligned
in the header of annotation cards.

* Move logic for adding a new, unsaved page note to AnnotationsService
* Render new-note button as a `LabeledButton` within `SelectionTabs`
* Remove `NewNoteBtn` component

To apply theming from settings, we need to be able to set inline styles
on buttons.

Use a simpler mixin for Notebook's "inner" container: we don't need
all the stuff in `panel`, `card-frame` suffices. This eliminates the
need to override a vertical rhythm rule.

This is the first time in my life I've ever found what seems like a
potentially valid use case for `!important`: assuring that a utility
class that establishes rhythm based on margins is able to do its job.

Typically, our components should not be styling their own margins, but
there are some cases where we do, e.g. the initial reset of button
styles, which sets `margin: 0`. (Components should style their own
padding, but margins are the domain of containing/parent elements).

These two `!important` rules allow two utility mixins that are explicitly
concerned with margins to trump the specificity of margin-resetting
rules on descendent elements.

See https://css-tricks.com/when-using-important-is-the-right-choice/

This PR makes the adder to reposition when the adder is visible and the
window is resized. In this way the adder is always close to the selected
text.

Closes #3194

Use the `ListenerCollection` utility to register and unregister
listener, similarly to other parts of the application.

Add sidebar-wide custom styling for "compact" icon buttons: icon-only
buttons with no touch-input min-size and tighter padding, as used in
the `TopBar`

Update components to use `IconButton` with `CompactIconButton` styling
where applicable.

* Labeled buttons should continue sizing font as 1em, icons default at
  1.25em (no change)
* Icon-only buttons should size icon at 1em (instead of 1.25em) because
  the icon _is_ the content

Update `AnnotationActionBar` to set local font size to 16px to get
desired icon sizing (@1em).

This will allow elements to set contextual 1em=16px for appropriate
icon sizing (in buttons)

`GroupListItem` and `GroupListSection` are never used outside of the
`GroupList` itself.

Bumps [karma](https://github.com/karma-runner/karma) from 6.2.0 to 6.3.1.
- [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/v6.2.0...v6.3.1)
Signed-off-by: dependabot[bot] <support@github.com>