Convert src/sidebar/components to ES modules

This mocking broke after the ES module conversion. Since the mocked
module just exports a set of constants, we can just avoid mocking it.

Export `updateModel` as a separate export rather than a property of the
default export, since this is how the test expects to import it.

Use the convert-to-es-modules package from the frontend-toolkit repo to
convert CommonJS/Node require syntax to ES modules.

As well as the module syntax conversion, this script also has the effect
of normalizing the sorting and grouping of imports according to the
following convention:

 - Imports are grouped into 3 categories: Vendor, same package but other
   directory (as calling module), same directory as calling module
 - Imports are sorted by module path

Import specifiers are untouched.

Convert sidebar entry point to ES modules

Bump sinon from 8.0.2 to 8.0.4

Bumps [@babel/preset-env](https://github.com/babel/babel) from 7.7.7 to 7.8.2.
- [Release notes](https://github.com/babel/babel/releases)
- [Changelog](https://github.com/babel/babel/blob/master/CHANGELOG.md)
- [Commits](https://github.com/babel/babel/compare/v7.7.7...v7.8.2)
Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Bumps [sinon](https://github.com/sinonjs/sinon) from 8.0.2 to 8.0.4.
- [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/v8.0.2...v8.0.4)
Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Bumps [@babel/preset-react](https://github.com/babel/babel) from 7.7.4 to 7.8.0.
- [Release notes](https://github.com/babel/babel/releases)
- [Changelog](https://github.com/babel/babel/blob/master/CHANGELOG.md)
- [Commits](https://github.com/babel/babel/compare/v7.7.4...v7.8.0)
Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Bumps [@babel/core](https://github.com/babel/babel) from 7.7.7 to 7.8.0.
- [Release notes](https://github.com/babel/babel/releases)
- [Changelog](https://github.com/babel/babel/blob/master/CHANGELOG.md)
- [Commits](https://github.com/babel/babel/compare/v7.7.7...v7.8.0)
Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Bumps [aws-sdk](https://github.com/aws/aws-sdk-js) from 2.597.0 to 2.601.0.
- [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/v2.597.0...v2.601.0)
Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Use the `convert-to-es-modules` script from the
hypothesis/frontend-toolkit repo to convert the sidebar entrypoint to ES
modules.

Because the code generated for `import` includes interop code to support
either ES or CommonJS modules, but migrating a module with a default
export changes its exports object, we need to migrate the module graph
"top-down" (ie. convert a module, then its dependencies).

Hoist CommonJS imports to top of file

In preparation for conversion to ES modules, hoist some remaining
non-top level `require` calls to the top level of the file.

Normalize module imports to an ES module-friendly format

In preparation for conversion to ES imports, hoist Node/CommonJS imports
to the top level of the module.

When converting to ES imports, store modules will default-export an
object rather than a set of named exports. Using destructuring here
confuses the conversion script.

In preparation for conversion to ES imports, hoist the Node/CommonJS
imports to the top level of the module.

This will avoid an issue with the export named `default` when the
majority of imports are converted in the next commit.

The transform-async-to-promises Babel plugin could end up inserting helper code
between the `@ngInject` comment and the associated function, breaking
the functionality of the angularjs-annotate Babel plugin. Work around
this by adding the `$inject` property to the function manually instead
of relying on the angularjs-annotate plugin to do it.

This issue only showed up locally when testing out a change to convert
the module's imports to ES module syntax.

Normalize several require statements into a form that can be handled
more easily by an automated tool to convert them to ES modules.

Establish `AnnotationOmega` component and add header and quote to it

Modify a mocking idiom that doesn't work with ES modules

We have an idiom in many tests where we import the "default export" from
a module and then access the `$imports` property on that
function/class/object in order to mock or unmock imports. For example:

```
const Widget = require('../widget');

beforeEach(() => {
  Widget.$imports.$mock(...);
});

afterEach(() => {
  Widget.$imports.$restore();
});
```

This won't work when the module under test is converted to an ES module
because the `$imports` object will become a separate export from the
module rather than a property of the default export.

Move `delete` and `flag` logic into `AnnotationActionBar` sub-component

Move the (straightforward) flag and delete logic into the
AnnotationActionBar component, near to where the UI interaction
takes place to lessen complexity of `Annotation`

Add `isHighlight` util function to `annotation-metadata`

Bump sinon from 8.0.1 to 8.0.2

Bump redux from 4.0.4 to 4.0.5

Bump terser from 4.4.3 to 4.5.1

Bump fetch-mock from 8.3.0 to 8.3.1