21792 Revert “Migration to PlatformDispatcher and multi-window #20496” (cla: yes, platform-android, platform-ios, waiting for tree to go green)

21806 Forward Error objects to uncaught exception handler if there is one. (cla: yes, platform-android)

21817 Enable clipRRect for android platform view hybrid composition (cla: yes, platform-android, waiting for tree to go green)

21839 [android] Refactor surface factory and wire in external view embedder (cla: yes, platform-android, waiting for tree to go green)

21841 [flutter_releases] Flutter 1.22.2 engine cherrypicks (cla: yes, platform-android, platform-ios)

21889 Fix incldues to be flutter/shell rather than shell/ (cla: yes, platform-android)