Adds a test that verifies that the view of the local time is the same in
the Dart isolate and the process that is running the test.

Specifically, this test is useful to verify that the code paths for
timezone retrieval do not break while the underlying FIDL protocols are
being refactored.

However, since the check is generally useful, the test is written as a
general flutter test.

Running this on Fuchsia required adding `fuchsia.intl.ProfileProvider`
to the CMX file that is used for all build Fuchsia packages.

Testing is a bit involved on Fuchsia.  You must build the Fuchsia
package `fluter/shell/common:shell_tests` and publish it to the dev
repository for your Fuchsia device.  It seems that a way to do so is to
modify the script `flutter/tools/fuchsia/build_fuchsia_artifacts.py` and
modify its function `GetTargetsToBuild` like so:

```
def GetTargetsToBuild(product=False):
  targets_to_build = [
    'flutter/shell/platform/fuchsia:fuchsia',
    'flutter/shell/common:shell_tests',
  ]
  return targets_to_build
```

Next, the Fuchsia packages need to be compiled and published.

Once done, the following `fx` invocation will run the test, assuming
that you have your Fuchsia setup:

```
fx shell run \
    fuchsia-pkg://fuchsia.com/shell_tests#meta/shell_tests.cmx \
    -- --gtest_filter=ShellTest.LocaltimesMatch
```

The converters are still in a separate target that must be included manually. This allows targets that depend on FML but not Dart runtime not have to depend on the runtime.

Adds a test that includes this target and tests image decompression from assets. There is also a test for the standalone DartConvertor in shell_unittests but not in fml_unittests be cause FML uni-tests cannot yet launch a VM. I will work on adding fixtures for those.

* Moves pointer event sanitizing to engine

* fix comment format

* fix formatting

* addressing comment

* fix format

* fix format

* addressing comment

Since this is currently only meant to be used by the embedding internally, the setter in Objective-C is only exposed via the FlutterDartProject private class extension. Unit tests have been added to the shell_unittests harness.

Fixes https://github.com/flutter/flutter/issues/37641

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.

This reverts commit aac33d1b.

Reason: flutter/flutter#40863

TBR: chinmaygarde, iskakaushik

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

This reverts commit b569e8c2.

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.

Using it, a Flutter app can monitor missing frames in the release mode, and a custom Flutter runner (e.g., Fuchsia) can add a custom FrameRasterizedCallback.

Related issues:
https://github.com/flutter/flutter/issues/26154
https://github.com/flutter/flutter/issues/31444
https://github.com/flutter/flutter/issues/32447

Need review as soon as possible so we can merge this before the end of May to catch the milestone.

Tests added:
* NoNeedToReportTimingsByDefault
* NeedsReportTimingsIsSetWithCallback
* ReportTimingsIsCalled
* FrameRasterizedCallbackIsCalled
* FrameTimingSetsAndGetsProperly
* onReportTimings preserves callback zone
* FrameTiming.toString has the correct format

This will need a manual engine roll as the TestWindow defined in the framework needs to implement onReportTimings.

Dart lints added:
* Avoid optional new
* Avoid optional const
* Prefer single quotes
* Prefer default assignment `=`

The callbacks can be wired in via the Settings object. Both runtime and shell unit-tests have been patched to test this.