69972 [flutter_tools] wrap http send in async guard (cla: yes, tool)

69987 [flutter_tools] remove material design schema, use dart code (cla: yes, f: material design, tool)

69997 move cupertino_icon template to 1.0.1 for null safety (cla: yes, team, tool)

70011 [flutter_tools] remove most globals from asset system and remove Cache manipulation in unit tests (cla: yes, tool)

70014 [flutter_tools] remove workaround for caching sound dill (a: null-safety, cla: yes, team, tool)

70023 Revert “Migrate Flutter gallery test to null safety” (cla: yes, f: cupertino, f: material design, team, tool)