Expose generateTestBootstrap() as public API in test harness (flutter…

…#17290)

This will allow external tools that wrap our test harness to share the
code that generates the test bootstrap.

This change exposed an issue whereby the LocalGoldenFileComparator
was being too strict in its URI handling, so this changes relaxes
that constraint as well (and adds associated tests).

Extract KernelCompiler class (flutter#16937)

Wraps the compile function in a class injected via the global context,
which makes it easier to mock in unit tests -- specifically tests for
AOT snapshotting, which already require pretty significant amounts of
mock inputs.

[fuchsia] Pass a dummy command to the ssh tunnel setup (flutter#16906)

* [fuchsia] Pass a dummy command to the ssh tunnel setup

* Address analyzer lint

* Update fuchsia_remote_debug_protocol

Roll engine to cb3376c (flutter#16841)

This contains the following commit:

flutter/engine@cb3376c Support different encodings in Image.toByteData() (flutter#16635)

Fix capitalization in README.md (flutter#16788)

Do exponential backoff for all exceptions in VMService::defaultOpenCh…

…annel. (flutter#16785)

We were trying to only catch WebSocketException, but in fact
SocketException can be thrown as well.

Fix a bug in the AnimatedChildSwitcher, add builders. (flutter#16250)

This fixes a rendering problem in the AnimatedChildSwitcher where it would add a new "previous" child each time it rebuilt, and if you did it fast enough, all of them would disappear from the page.

It also expands the API for AnimatedChildSwitcher to allow you to specify your own transition and/or layout builder for the transition.

Fixes flutter#16226

Update dependencies (flutter#16442)

[fuchsia] Fixes for Fuchsia hot reload (flutter#16317)

Adding onTapDown and onTapCancel to InkWell (flutter#16190)