Implement basic state management for ARKitCoordinator to provide enough support for immersive-ar-session.html to support starting and exiting an immersive AR session and handle messages from the page.
rdar://problem/116502232
Pull request: https://github.com/WebKit/WebKit/pull/18743
Committed 269052@main (581471a69f32): <https://commits.webkit.org/269052@main> Reviewed commits have been landed. Closing PR #18743 and removing active labels.
Re-opening for pull request https://github.com/WebKit/WebKit/pull/18979
Committed 269239@main (cebf8bf46cd6): <https://commits.webkit.org/269239@main> Reviewed commits have been landed. Closing PR #18979 and removing active labels.