* Trial PR to use an engine that has the null safety unfork CL in it.

* Fix mack specification for test.

* enable macOS desktop

* enable all configs on CI

* Update track_widget_creation_enabled_task.dart

* Update framework.dart

* remove FLUTTER_WEB

* remove config environment variables

* configure in correct spot

This is required to run the macOS twc enabled devicelab test.

Ensure --no-track-widget-creation is piped through android/macOS. Adds integration testing for iOS/android/macOS

An upcoming Dart SDK change
(https://github.com/dart-lang/sdk/commit/fa2fd41166db35afa4777e63f900e83d25709c5c)
changes the precise text of the exception generated by `utf8.decode`
if a non-UTF8 file is found.  This is causing a breakage in the Dart
team's `flutter-analyze` bot (and will presumably cause a breakage in
the corresponding Flutter bot as soon as this change is rolled into
Flutter).  To avoid this breakage, the bot shouldn't rely on the exact
exception text; it is sufficient to simply catch a FormatException.

2037e0f18 Roll src/third_party/dart c3ce87355614..d5af40b640f7 (1 commits) (flutter/engine#18110) (#56258)

Redirects stdout/stderr in the Windows template when creating a console. This fixes the console opened when running from Visual Studio to actually show output, instead of being empty.

Fixes #53169

7a492012a Roll src/third_party/skia 80cab814091d..57f289d7423c (1 commits) (flutter/engine#18105) (#56233)

813fd04c7 Roll src/third_party/dart a42e6ac0356d..c3ce87355614 (3 commits) (flutter/engine#18103) (#56225)

94e6baa75 Roll src/third_party/dart be1f85847fd5..a42e6ac0356d (1 commits) (flutter/engine#18102) (#56215)

86c0c54be Roll src/third_party/dart eca696c0268f..be1f85847fd5 (3 commits) (flutter/engine#18100) (#56187)

d0bcc6980 Roll src/third_party/skia 64964bb1150e..80cab814091d (1 commits) (flutter/engine#18099) (#56182)

edf65e286 Roll fuchsia/sdk/core/linux-amd64 from cIjMH... to Rp56G... (flutter/engine#18098) (#56177)

* Run encode kn character encoding tool when gen_localizations is run

* Add test that ensures *_kn.arb files are properly encoded/escaped in order to be checked in

* Fix *_no.arb test to not incorrectly pass

Introduce BuildSystem.buildIncremental, which keeps an in-memory cache of timestamps instead of file hashes. This will be used to implement localization generation through the same build system API.

Ensure iOS and android builds can be correctly cached. Use the performance-measurement-file to verify that all targets were skipped on the second invocation. This is only run on the flutter_gallery build.

This adds an ExcludeFocus widget that prevents widgets in a subtree from having or obtaining focus. It also adds the ability for a FocusNode to conditionally prevent its children from being focusable when it isn't focusable (i.e. when canRequestFocus is false).

It does this by adding an descendantsAreFocusable attribute to the FocusNode, which, when false, prevents the descendants of the node from being focusable (and removes focus from them if they are currently focused).