19458 Added the ability to set properties in interface builder for FlutterViewController (cla: yes, platform-ios)

19684 Refactor initial route code (cla: yes, platform-ios)

19728 Fix Mac / iOS builds (cla: yes, platform-ios)

19785 Fix loss of negative text selection ranges (cla: yes, platform-ios)

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

19819 remove obsolete check on FlutterPlatformViewsController::OnCreate (cla: yes, platform-ios, waiting for tree to go green)

19826 fix On iOS, dialog titles are announced twice (cla: yes, platform-ios)