PWA Transparent Area Event Penetration Fix and Window Controls Overlay Related Code Cleanup

The impact of this change on WebView2Mac is mainly reflected in the modification of the event handling mechanism at the Remote Cocoa layer. Specific impacts include: 1) Removal of the UpdateWindowControlsOverlay interface and its implementation in Remote Cocoa, which means that if downstream WebView2Mac code relies on this interface to handle similar transparent region overlay functionality, it may be affected; 2) Deletion of the custom hitTest method and _windowControlsOverlayRect cache in WebContentsViewCocoa, altering the event routing mechanism, which may impact similar transparent region event handling logic in WebView2Mac; 3) Removal of the UpdateWindowControlsOverlay mojo interface in WebContentsNSViewBridge, so if WebView2Mac uses a similar inter-process communication mechanism to manage transparent overlay regions, alternative solutions will be needed. However, since these changes are mainly targeted at the Window Controls Overlay feature for PWAs, and WebView2Mac, as an embedded web control, typically does not need to handle window control button overlay scenarios, the impact on core functionality is relatively limited. Nevertheless, if downstream implementations have custom transparent region or event penetration requirements, relevant adjustments may be necessary.