84411 Add Designed for iPad attach destination for ARM macOS (platform-ios, tool, platform-mac, cla: yes, waiting for tree to go green, platform-target-arm)

84443 [flutter_tools] reduce mocking in error handling io (tool, cla: yes, waiting for tree to go green)

84469 Migrate build_macos and web_test_compiler to null safety (team, tool, cla: yes, waiting for tree to go green, a: null-safety)

84470 Fix compile expression in tests when precompiled dill files are used. (tool, cla: yes, waiting for tree to go green)

84476 Turn on avoid_dynamic_calls lint, except packages/flutter tests, make appropriate changes. (a: tests, team, tool, framework, f: material design, a: accessibility, a: internationalization, cla: yes, f: cupertino, d: examples)