78113 [flutter_tools] Add support for custom devices (cla: yes, tool, waiting for tree to go green)

78140 CupertinoTextField to show disabled background color when decoration is null (cla: yes, f: cupertino, framework, waiting for tree to go green)

78143 Update docs to reflect Null Safety (cla: yes, d: api docs, d: examples, documentation, framework)

78161 Add removeListenerWhileNotifying benchmark for ChangeNotifier (cla: yes, framework, team, waiting for tree to go green)

78166 [flutter_tools] Fix avdmanager path detection (cla: yes, tool, waiting for tree to go green)

78202 Dedup CupertinoAlertDialog and CupertinoActionSheet source code (cla: yes, f: cupertino, framework, waiting for tree to go green)