21522 Fix windows popup when unit tests have failures (cla: yes)

21523 Add missing returns in system channels handlers (affects: desktop, cla: yes, needs tests, platform-windows)

21525 Smooth window resizing on macOS (affects: desktop, cla: yes, needs tests, platform-macos, waiting for tree to go green)

21526 iOS: only add explicit transactions when there are platform views (only on main threads) (cla: yes, platform-ios, waiting for tree to go green)

21527 fuchsia: Remove Opacity hole-punch (cla: yes, platform-fuchsia)

21529 Roll Fuchsia Mac SDK from aO19K7Ut2… to U2Cd8uL4-… (cla: yes, waiting for tree to go green)