77194 [flutter_releases] Fix symlinks in prepare_packages script (a: tests, cla: yes, engine, f: cupertino, f: material design, framework, team, tool)

77263 Re-land “Toggable Refactor (#76745)” (a: accessibility, cla: yes, f: material design, framework, team, waiting for tree to go green)

77286 Revert “[showModalBottomSheet] fix: showModalBottomSheet does not mov… (cla: yes, f: material design, framework, waiting for tree to go green)

77294 Enable avoid_unnecessary_containers lint (a: accessibility, a: tests, cla: yes, f: cupertino, f: material design, framework, team, waiting for tree to go green)