20538 Clean up the CI scripts and make it so that they can be run from anywhere (cla: yes)

20542 Started stubbing in the FlutterView property of the mock FlutterViewControllers (cla: yes, platform-ios)

20550 Revert “[windows] Expose the binary messenger from FlutterEngine” (cla: yes)

20551 [windows] Expose the binary messenger from FlutterEngine (cla: yes)

20557 Fix font sorting problem due to iOS 14 fonts being broader (cla: yes)

20564 Revert “Create PlatformView instance right after method channel call from Dart (#20500)” (cla: yes, platform-android)

20568 Reland: Create PlatformView instance right after method channel call from Dart (cla: yes, platform-android, platform-ios)