* Modifies accessibility bridge to populate new node fields in semantics API.

* Adds additional UTs and fixes logic for breaking up updates for nodes with large values.

* Chaged tests to set node flags using bitwise-or instead of addition.

* Address bug in update size arithmetic.

* Fixes issue in TruncatesLargeValue unit test causing unexpected deletes.

* Fixes expected number of updates in BatchesLargeMessages unit test to reflect expected values now that node states are populated.

android.os.Parcelable was added in commit
6d5aaa09 but never used.

Make sure that a text range at the end of the string is still valid.

We now have one mutex guarding all accesses to
the underlying task heaps. This simplifies the more granular
but bug prone mechanism of having striped locks.

This also re-enables GPUThreadMerger tests that are currently
disabled due to their flaky nature. The scenario that gets fixed by this
change is as follows:

1. Thread-1: We lock `queue_meta_mutex_` and grab locks on `queue_1` and release the meta mutex.
2. Thread-1: We add an Observer on `queues` object.
3. Thread-2: We lock `queue_meta_mutex_` and grab locks on `queue_2`.
4. Thread-2: We try to dispose all the pending tasks on `queue_2` which calls `erase` on `queues`.

The above situation is not thread safe without having 1 lock.

Note: This increases the contention on one lock and could potentially be bad for perf. We are
explicitly making this trade-off towards reducing the complexity.

Fixes: https://github.com/flutter/flutter/issues/49007

* Ensure fields of Rect and OffsetBase classes are optimized as non-null.

* Update web_ui and formatting

This also adds a dependency on SwiftShader's Vulkan frontend.

- Enable dynamically loaded fonts
- Fix addOval
- Fix getBoxesForRange for negative ranges

Fixes a warning when compiling in Visual Studio on Windows.

- added temporary ignore for annotate_overrides analyzer warning,
  will remove the ignore in a follow-up PR after the SDK change
  https://dart-review.googlesource.com/c/sdk/+/134561 lands.
- run dartfmt

RasterCache::Get() methods were not updating the RasterCache::Entry
access_count and used_this_frame fields, as is done in
RasterCache::Prepare(). This can result in onscreen images being evicted
from the cache as new entries are created (e.g. as new elements scroll
onscreen).

We don’t run this test on bots because we don’t want timeouts on any tests. This
only runs locally as a sanity check for timers.