25797 Fix a11y tab traversal (cla: yes, platform-web)

25812 web: improve engine dev cycle on Windows (cla: yes, platform-web)

25830 Fix a11y placeholder on desktop; auto-enable engine semantics (cla: yes, platform-web)

25842 Move path part files to libraries (cla: yes, platform-web)

25843 [flutter_releases] Flutter Stable 2.0.6 Engine Cherrypicks (platform-ios, platform-android, cla: yes, platform-web, platform-macos, platform-linux, platform-windows, platform-fuchsia, embedder)

25863 Move more parts to libraries. (cla: yes, platform-web)

25866 [web] Fix some regex issues in the sdk_rewriter (cla: yes, platform-web)