19787 [web] Improve perf and code size of line breaker (cla: yes, platform-web, waiting for tree to go green)

19788 Makes IOS dispatch showOnCcreen action for header semantics nodes (cla: yes, platform-ios, waiting for tree to go green)

19791 Manual Dart SDK roll (cla: yes)

19792 fuchsia: Allow setting thread-name (cla: yes, platform-fuchsia)

19794 Fix targets param in build_fuchsia_artifacts (cla: yes, platform-fuchsia)

19796 FlRenderer cleanup in preperation for Wayland support (cla: yes)

19810 [null-safety] remove package references from flutter frontend-server test, ci analyze (cla: yes, waiting for tree to go green)