76400 [flutter_tools] Refactor DeferredComponents validator and add build target (cla: yes, tool, waiting for tree to go green)

76403 Revert “Reland “Roll Engine from 6993cb229b99 to c217d9d06e4f (60 revisions) (#76352)”” (cla: yes, engine, team)

76406 Do not show embedding warning for plugins when example app is missing (cla: yes, platform-android, tool, waiting for tree to go green)

76409 Roll Gallery (required by the latest engine update and Dart SDK) (cla: yes, team)

76414 Skip assemble version check in tool backend scripts (cla: yes, tool)