Fixes a few issues with Windows text input:
- Filters out ASCII control characters
- Filters out lead surrogates, which aren't valid UTF-16 on their own so will cause assertion failures if sent to Flutter
- Adds a bandaid fix for a crash due to mismatches in indexing in the C++ and Dart text models. (A better fix would be to use UTF-16 and add surrogate pair handling to deletion and forward/back; that will be a later PR since it has a larger scope.)

Fixes https://github.com/flutter/flutter/issues/54879

The raster cache is critical for good performance. This
enables the cache and provides a GrContext to ScopedFrame
instances so the cache can be efficiently populated.

Small increase in peak GPU memory usage is expected from
this change. Otherwise, no change in behavior expected.

Fixes https://github.com/flutter/flutter/issues/54950Co-authored-by: NDavid Reveman <reveman@google.com>

16 MiB -> 28 MiB

Same size as what would be used on a 1024x600 display if we
allowed the common engine code to adjust this.
Co-authored-by: NDavid Reveman <reveman@google.com>

Fixes https://github.com/flutter/flutter/issues/54275

* Convert semantics_node from SkMatrix44 to SkM44

* Guard canvas virtuals so we can remove legacy didConcat44

SkMatrix44 is also deprecated, so start transitioning to SkM44.

* Fix formatting

The NSEvent->Flutter event conversion code for pointer events was
multiplying seconds by nanoseconds per milliseconds. While this does end
up giving the right number of microseconds, it's a very confusing way to
write it.

Fixes several bugs in the clipboard code, and makes some structural
improvements:
- Adds scoped wrappers for clipboard open/close and global lock/unlock,
  to prevent missing cleanup, fixing at least one case where the lock
  was not released.
- Adds the relevant window handle to the clipboard calls, since the docs
  suggest that some operations won't work without one.
- Adds a missing clear step to setting the clipboard data.
- Switches from TEXT to UNICODETEXT to handle non-ASCII text correctly.
  - To enable that, adds UTF-16/-8 conversion utilities built on the
    Win32 APIs (rather than the deprecated std::codecvt functions, as
    have been previously used in the engine).
- Fixes handling of getting data when the clipboard is empty, correctly
  returning null.
- Passes more errors back through the method channel, with details, for
  easier debugging of future issues.

Fixes https://github.com/flutter/flutter/issues/54226

Desktop embedding dependencies can trigger gn-generation-time
requiremenets; e.g., the Linux embeddings have pkg-config dependencies.
This can be problematic in some build environments, such as building
flutter_engine.so with a custom sysroot where those higher-level
dependencies aren't available.

This flag allows generating build files that don't have those
dependencies.

- Adds an explicit option for not building the GLFW embedding.
- Disables GLFW by default on Windows, where it's no longer the
  uploaded embedding.
- Moves the X11 pkg-config, which is only used by the GLFW embedding,
  behind the GLFW build flag.

Update docstrings for typos and grammar style specified in the style guide.

Makes InvokeMethod's reply a high-level response object, rather than
binary data, matching the abstraction level of the class (and the other
languages' implementations).

In support of that:
- Adds the logic to the codecs to decode response envelopes, which had
  never been implemented.
- Adds a convience implementation of MethodResult that forwards to
  lambdas, so that one-off invocation handlers are easier to write.

Also simplified BinaryMessenger's API so that subclasses only need to
implement one version of Send, rather than two almost-identical versions.

Fixes https://github.com/flutter/flutter/issues/53223

The BaseInputConnection superclass does not call endBatchEdit
in setSelection and therefore does not implicitly cause
InputConnectionAdaptor to send a state update.

Some input modes such as numeric keypads will not function without
these updates.

fx_log_init was already a no-op, and was eliminated in the latest
Fuchsia SDK.

See: https://fuchsia.googlesource.com/fuchsia/+/47e568475f535c00f53c86e19ff4d8736a7b261f

Fixes https://github.com/flutter/flutter/issues/53117

Test added:
- ShellTest.CanLoadSkSLsFromAsset

* Revert getSystemGestureExclusionRects and setSystemGestureExclusionRects 

* Remove references to removed PlatformChannelTest.java file

This reverts commit f6b8eda7.

This event goes from now -> current vsync target time
to avoid the limitations as seen in https://github.com/flutter/flutter/issues/54095#issuecomment-610636237

This event also tags additional metadata to capture
`vsync_transitions_missed` considering the refresh rate of the display.