72020 Move macOS Podfile logic into the tool (cla: yes, platform-mac, t: xcode, team, tool)

72040 Prepare to migrate API doc samples and snippets to null safety (cla: yes, f: cupertino, f: material design, framework, team, waiting for tree to go green)

72079 [flutter_releases] Flutter Framework Stable 1.22.5 cherrypicks (a: tests, cla: yes, d: examples, engine, f: cupertino, f: material design, framework, team, tool)

72092 Revert “Migrate devicelab to package:vm_service” (cla: yes, team, tool)

72136 [dev] Don’t use await for on stdout and stdin; pass local engine argument (cla: yes, team)