58808 Introduce inherited navigator observer and refactor hero controller (cla: yes, f: cupertino, f: material design, framework, waiting for tree to go green)

59115 Modernize selection menu appearance (cla: yes, f: cupertino, f: material design, framework, platform-android, waiting for tree to go green)

59120 Deprecate WhitelistingTextInputFormatter and BlacklistingTextInputFormatter (a: tests, cla: yes, f: cupertino, f: material design, framework, team, waiting for tree to go green)

59160 Remove unused import which shares prefix name with a used import. (a: internationalization, cla: yes, f: cupertino, f: material design)

59186 Opt out nnbd in packages/flutter (a: accessibility, cla: yes, f: cupertino, f: material design, framework)