Switch the MacOS Desktop embedder to using a thread configuration where the platform and render task runners are the same. (#13300)

Also creates a new test harness for the desktop embedder framework target and adds a test that launches a headless engine in this new thread configuration.

Fixes https://github.com/flutter/flutter/issues/17579

The FIDL service `fuchsia.intl.PropertyProvider` is a service that
the flutter runner can use to obtain information on system preferred
locales.

This change sends a platform message "setLocale" on the channel
"flutter/localization", based on the values provided by the above
mentioned FIDL service.

Credit: most of this was initially written by @kpozin; I ported it
to out-of-tree flutter engine.

Tested:

1. Compile and publish the unit tests package as shown in
   the script below.
2. In a Fuchsia repository (pointed to by `$FUCHSIA_DIR`), run
   `fx serve`
3. `fx shell run fuchsia-pkg://fuchsia.com/flutter_runner_tests#meta/flutter_runner_tests.cmx`

The script used to update the unit tests.

```bash

set -x

FLUTTER_ENGINE_DIR="${FLUTTER_ENGINE_DIR:-$HOME/fx/flutter/engine/src}"
readonly OUT_DIR="${FLUTTER_ENGINE_DIR}/out"

(
  cd ${FLUTTER_ENGINE_DIR}
  ./flutter/tools/gn --fuchsia --fuchsia-cpu x64 --unoptimized
  ninja -j 100 -C "${OUT_DIR}/fuchsia_debug_unopt_x64"
  cp "${OUT_DIR}/compile_commands.json" "${FLUTTER_ENGINE_DIR}"

  echo "Publishing the tests package"
  "${FLUTTER_ENGINE_DIR}/fuchsia/sdk/linux/tools/pm" publish \
    -a -r $FUCHSIA_DIR/out/release/amber-files \
    -f "${FLUTTER_ENGINE_DIR}/out/fuchsia_debug_unopt_x64/flutter_runner_tests-0.far"
)
```

SkiaUnrefQueue should be empty at destruction time.  If the queue is nonempty,
then there will be a pending drain task that will hold a reference to the
queue.  The queue can only be destructed after the drain completes and the
reference is dropped.

Drains must only be done on the queue's task runner thread, which may not be
the thread where the queue is destructed.

* Update CanvasKit to 0.7.0 and flesh out painting

This allows us to fix some bugs in the CanvasKit backend.

- Implement RRect where the radii are different
- Implement drawDRRect
- Implement ColorFilter
- Implement the correct `arcTo` for `arcToPoint`

* update licenses

* Respond to review comments

- Add TODO to avoid unnecessary conversions
- Don't set CanvasKit to default
- Fix licenses file

* Add ==, hashCode, and toString back to ColorFilter API

* Draw vertices to shared offscreen canvas on browsers that support OffscreenCanvas.
* Move gl rendering code to render_vertices.dart.
* Reuse shaders and program across calls.

Adds a task runner, and exposes API to allow application-level runloops to know when they need to next call the API to process engine events. Internally, sends null events to wake up the app runloop when new events are scheduled to ensure the wait time is updated accordingly.

Fixes #36420

Fixes https://github.com/flutter/flutter/issues/42704.

Move surface-based SceneBuilder implementation under surface/

* Implement path.transform

Texture unregistration is finished on the GPU thread. The FlutterTexture implementation might not know when it is finished which leads to a race condition. Adding this callback so the FlutterTexture is aware of end of the unregistration process.

For https://github.com/flutter/flutter/issues/40686

Unit tests added:
- CacheSkSLWorks
- VisitFilesCanBeCalledTwice
- CanListFilesRecursively

* Roll dart to aece1c1e92.

Changes since last roll:
```
aece1c1e92 Update compile_flutter.sh after vm -> frontend_server rename
9293e26fc9 [gardening] Fix flutter hhh patch.
13fbf569f6 [flutter] split frontend_server from vm package
a389015083 Rewrite MethodInvocation to FunctionExpressionInvocation when the target is not a method.
ae251757a9 [vm,aot,bytecode] Performance fixes
01ebf92dde [VM] Consume extension member/is late flag setting when reading kernel file.
8e05cd278c [vm, bytecode] Emit bytecode without ASTs by default.
4539536b34 [eventhandler] generalize socket initialization
7115687beb NNBD i13n: Add a description for discarding just the condition
2bcaf02582 (origin/base) Update dartdoc to 0.28.7.
a0e8c7712d [dart2js] New RTI: Prevent elision of precomputed1 and remove unneeded read.
c38e19cbbe [vm/compiler] bit utilities
f918214f36 Add a unit test reproducing issue #38352.
ad47b1ca64 Remove summary1, part 2.
0881a4a691 Reland "Deprecate TypeParameterTypeImpl.getTypes()"
d93a6b596b Prepare to publish analyzer version 0.38.5
d5feab0c53 [vm] Create builds for LeakSanitizer, MemorySanitizer and ThreadSanitizer.
8c5236f55e [vm/ffi] Fix host-target word mismatch breaking AOT callbacks in ARM_X64.
5f7b837195 Remove unused FunctionElementImpl_forLUB.
2c75771611 Write and read the static type of IntegerLiteral.
b00453c68a Create synthetic FunctionType in quick fixes.
897e197dd4 Flow analysis: Update AssignedVariablesVisitor to track functions/methods.
55466fd3cc Flow analysis: Remove AssignedVariables.capturedAnywhere.
0a5cf36f14 Make exitFunctionBody safer.
```

* Update license hash

This reverts commit c2879cae.

Additionally, we fix https://github.com/flutter/flutter/issues/40863 by adding a secondary VSYNC callback.

Unit tests are updated to provide VSYNC mocking and check the fix of https://github.com/flutter/flutter/issues/40863.

The root cause of having https://github.com/flutter/flutter/issues/40863 is the false assumption that each input event must trigger a new frame. That was true in the framework PR https://github.com/flutter/flutter/pull/36616 because the input events there are all scrolling move events. When the PR was ported to the engine, we can no longer distinguish different types of events, and tap events may no longer trigger a new frame.

Therefore, this PR directly hooks into the `VsyncWaiter` and uses its (newly added) secondary callback to dispatch the pending input event.

* Add windows font change logic

* update

* fix comment

Added unit tests for method channels.

This reverts commit aac33d1b.

Reason: flutter/flutter#40863

TBR: chinmaygarde, iskakaushik

* [flutter_runner] Move from runner context to component context

* remove the file references

Account for root surface transformation on the surfaces managed by the external view embedder. (#11384)

The earlier design speculated that embedders could affect the same
transformations on the layers post engine compositor presentation but before
final composition.

However, the linked issue points out that this design is not suitable for use
with hardware overlay planes. When rendering to the same, to affect the
transformation before composition, embedders would have to render to an
off-screen render target and then apply the transformation before presentation.
This patch negates the need for that off-screen render pass.

To be clear, the previous architecture is still fully viable. Embedders still
have full control over layer transformations before composition. This is an
optimization for the hardware overlay planes use-case.

Fixes b/139758641

* Improve the CanvasKit backend for Flutter Web

- Improve font handling by trying to load a "normal" font face
  instead of using the first face matching the family.
- Implement Vertices and drawVertices

* Add license header to vertices.dart

* Remove unused 'encodedPositions'

* Delete commented old code. Don't use Skia by default

* Add `vertices.dart` to licenses file

Added channel buffers to 'ui' so that messages have a place to
go until message handling is setup.

Makes the plugin registration structure consistent with macOS. This will
be used in generated plugin registrant files rather than a specific
implemenation class, so this helps unblock the creation of generated
registrants on Windows and Linux.

Additionally, we now use the engine directly as a delegate instead of storing potentially dead runtime_controller.

Unit tests have been updated to include an engine restart check which would fail before the fix.

This fixes https://github.com/flutter/flutter/issues/40303

Creates a starting point for an app delegate. For now it just
incorporates the menu and window renaming functionality that's currently
in the FDE example, but in the future this will also do forwarding of
application lifecycle events to plugins.

Fixes https://github.com/flutter/flutter/issues/32419

This reverts commit b569e8c2.

Ported from the original implementation in the Topaz tree.

- Add a custom `PlatformPlugin` that spins up a server waiting for test to request a screenshot.
  - When a screenshot is requested the plugin talks to Chrome via the debug port, captures a screenshot, and compares it with a golden file
- This PR also adds proper CLI for `dev/test.dart` with an `ArgParser` for future extension into a proper developer tool for the team.
  - As a first couple of features, it adds `--debug` option to launch Chrome in debug mode, a `--target` option to choose a single test to run rather than all tests, and `--shard` option to choose a subset of tests to run.

Limitations:
 - While screenshot test will run on Cirrus, they are configured to not fail on Cirrus. Need to solve Chrome version skew.
 - Stack maps do not work yet (you get stacks, but they are nonsensical)
 - When requesting a single test, build_runner builds all tests anyway
 - Nothing but desktop Chrome is supported
 - Nothing but Linux is supported
 - There's no Chrome version pinning; currently assumed stable Chrome channel

Fixes https://github.com/flutter/flutter/issues/31086

This patch is a lower level implementation of
https://github.com/flutter/flutter/pull/36616 that would only impact iOS
engine, and host unittests.