Convert mocking to mockable imports (3/4)

This enables mocking of the `anchoring/html` module in tests without having
to patch the `anchoring` property after the class is constructed.

Convert mocking to mockable-imports (2/4)

Convert remaining uses of proxyquire to babel-plugin-mockable-imports,
except for modules written in CoffeeScript, as the Babel plugin needs an
update to support the way groups of `<var> = require(<module>)`
statements get compiled.

Bump @babel/preset-env from 7.4.3 to 7.4.4

Bump scroll-into-view from 1.9.5 to 1.9.6

Bumps [@babel/preset-env](https://github.com/babel/babel) from 7.4.3 to 7.4.4.
- [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/v7.4.3...v7.4.4)
Signed-off-by: dependabot[bot] <support@dependabot.com>

Bump @babel/core from 7.4.3 to 7.4.4

Bump enzyme-adapter-preact-pure from 1.13.0 to 1.13.1

Bump babel-plugin-istanbul from 5.1.2 to 5.1.3

Merge pull request #1096 from hypothesis/dependabot/npm_and_yarn/babel-plugin-transform-async-to-promises-0.8.10

Bump babel-plugin-transform-async-to-promises from 0.8.9 to 0.8.10

Bumps [babel-plugin-istanbul](https://github.com/istanbuljs/babel-plugin-istanbul) from 5.1.2 to 5.1.3.
- [Release notes](https://github.com/istanbuljs/babel-plugin-istanbul/releases)
- [Changelog](https://github.com/istanbuljs/babel-plugin-istanbul/blob/master/CHANGELOG.md)
- [Commits](https://github.com/istanbuljs/babel-plugin-istanbul/compare/v5.1.2...v5.1.3)
Signed-off-by: dependabot[bot] <support@dependabot.com>

Note that the exports of the `anchoring/html` module are captured when
the class is constructed, so cannot be mocked later via `$imports`.
Instead the created `Guest` object has to be monkey-patched.

Convert proxyquire mocking of several CoffeeScript modules.

Merge pull request #1098 from hypothesis/dependabot/npm_and_yarn/babel-plugin-mockable-imports-1.3.1

Bump babel-plugin-mockable-imports from 1.2.0 to 1.3.1

Bumps [babel-plugin-mockable-imports](https://github.com/robertknight/babel-plugin-mockable-imports) from 1.2.0 to 1.3.1.
- [Release notes](https://github.com/robertknight/babel-plugin-mockable-imports/releases)
- [Changelog](https://github.com/robertknight/babel-plugin-mockable-imports/blob/master/CHANGELOG.md)
- [Commits](https://github.com/robertknight/babel-plugin-mockable-imports/compare/v1.2.0...v1.3.1)
Signed-off-by: dependabot[bot] <support@dependabot.com>

Bumps [babel-plugin-transform-async-to-promises](https://github.com/rpetrich/babel-plugin-transform-async-to-promises) from 0.8.9 to 0.8.10.
- [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/v0.8.9...v0.8.10)
Signed-off-by: dependabot[bot] <support@dependabot.com>

Bumps [enzyme-adapter-preact-pure](https://github.com/preactjs/enzyme-adapter-preact-pure) from 1.13.0 to 1.13.1.
- [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/commits)
Signed-off-by: dependabot[bot] <support@dependabot.com>

Bumps [@babel/core](https://github.com/babel/babel) from 7.4.3 to 7.4.4.
- [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/v7.4.3...v7.4.4)
Signed-off-by: dependabot[bot] <support@dependabot.com>

Bumps [scroll-into-view](https://github.com/KoryNunn/scroll-into-view) from 1.9.5 to 1.9.6.
- [Release notes](https://github.com/KoryNunn/scroll-into-view/releases)
- [Changelog](https://github.com/KoryNunn/scroll-into-view/blob/master/CHANGELOG.md)
- [Commits](https://github.com/KoryNunn/scroll-into-view/commits)
Signed-off-by: dependabot[bot] <support@dependabot.com>

Use context API to pass Angular services to React components

Instead of handling passing of Angular services to components directly
in `wrapReactComponent`, instead make the Angular `$injector` service,
from which references to all other services can be obtained, available
to the component tree via a `ServiceContext` provider.

Child components can then get references to services either using the
`withServices` wrapper, which looks up services and passes them as
props, or by using `useContext(ServiceContext)` to get a reference to
the injector directly.

To support accessing Angular services from nested React components
without having to pass them through each parent, create a helper which
wraps a component to look up service dependencies via an injector
exposed using the context API, and inject the dependencies as props.

Introduce a new approach to mocking modules in tests

Remove fragment anchoring support

Bump @octokit/rest from 16.24.1 to 16.25.0

Bump mocha from 6.1.3 to 6.1.4

Bump sinon from 7.3.1 to 7.3.2

Bump karma from 4.0.1 to 4.1.0

Bump gulp from 4.0.0 to 4.0.1

Bump babel-plugin-istanbul from 5.1.1 to 5.1.2

Bump enzyme-adapter-preact-pure from 1.12.0 to 1.13.0

Bump preact from 10.0.0-alpha.4 to 10.0.0-beta.0

Bumps [karma](https://github.com/karma-runner/karma) from 4.0.1 to 4.1.0.
- [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/v4.0.1...v4.1.0)
Signed-off-by: dependabot[bot] <support@dependabot.com>

Bumps [enzyme-adapter-preact-pure](https://github.com/preactjs/enzyme-adapter-preact-pure) from 1.12.0 to 1.13.0.
- [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/v1.12.0...v1.13.0)
Signed-off-by: dependabot[bot] <support@dependabot.com>

Bumps [@octokit/rest](https://github.com/octokit/rest.js) from 16.24.1 to 16.25.0.
- [Release notes](https://github.com/octokit/rest.js/releases)
- [Commits](https://github.com/octokit/rest.js/compare/v16.24.1...v16.25.0)
Signed-off-by: dependabot[bot] <support@dependabot.com>

Bumps [sinon](https://github.com/sinonjs/sinon) from 7.3.1 to 7.3.2.
- [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/v7.3.1...v7.3.2)
Signed-off-by: dependabot[bot] <support@dependabot.com>