12266 Reland add some AppLifecycleTests (cla: yes)

12267 [macos] Stops keeping track of text input models (cla: yes, platform-macos)

12268 Close the tree (cla: yes)

12269 a11y: expose max character count for text fields (cla: yes)

12272 Revert “Close the tree” (cla: yes)

12273 Clean up after AppLifecycleTests (cla: yes)

12274 Store screenshot test output as Cirrus artifacts; do fuzzy comparison of non-matching screenshot pixels (cla: yes)

12275 Shuffle test order and repeat test runs once. (CQ+1, cla: yes)

12276 Add system font change listener for windows (cla: yes)