21669 [flutter_releases] Flutter 1.22.1 Engine Cherrypicks (cla: yes, platform-android, platform-ios)

21670 [macOS] Allow loading of AOT snapshots and instructions from elf bundle (cla: yes, waiting for tree to go green)

21676 Roll Skia from a7f69c290667 to 041fd0ad7d93 (5 revisions) (cla: yes, waiting for tree to go green)

21677 Pass angles for SweepGradient in degrees, not radians (cla: yes, platform-web)

21678 Roll Dart SDK from 9560a32779fc to 8f1a96317589 (12 revisions) (cla: yes, waiting for tree to go green)