83522 [flutter_tools] remove more mocks from cache_test (tool, cla: yes, waiting for tree to go green)

83530 Add a more complete app template for Flutter (skeleton) (team, tool, cla: yes, waiting for tree to go green)

83732 use old Edge-compatible JavaScript in index.html (tool, cla: yes)

83744 Fixed large amount of spelling errors (a: tests, team, tool, framework, f: material design, a: accessibility, a: internationalization, cla: yes, f: cupertino, d: examples, waiting for tree to go green)

83803 [flutter_tools] always use device.stopApp (tool, cla: yes, waiting for tree to go green)

83817 Migrate project.dart and all dependencies to null safety (team, tool, cla: yes, a: null-safety)