18601 Rework GLContextSwitch, get rid of RendererContextManager (cla: yes)

18602 Roll Skia from e4b4ca1050b9 to e90473dc7da6 (27 revisions) (cla: yes, waiting for tree to go green)

18604 [web] Fix child removal after reuse by other BitmapCanvas (cla: yes)

18607 created a linter that runs clang-tidy (cla: yes)

18610 Update 1.17 engine hash to Dart 2.8.3 (cla: yes)

18612 Roll Dart SDK from 9e3b0289197d to e007545c42fd (43 revisions) (cla: yes, waiting for tree to go green)