webview2: Add Microsoft WebView2 based web browser source
Limitations:
- WebView2 does not support off-screen rendering
- will be rendered on hidden HWND and then we do read it back via Windows Graphics Capture API
- https://github.com/MicrosoftEdge/WebView2Feedback/issues/547
- Audio streams will be mixed by a single WebView2 process and rendered
- Applications do not have any control to the audio stream (only mute/unmute is possible)
- Now audio will be just muted
- https://github.com/MicrosoftEdge/WebView2Feedback/issues/2236
- https://github.com/MicrosoftEdge/WebView2Feedback/issues/41
- Applications do not have any control to the audio stream (only mute/unmute is possible)
- Keyboard input is not implemented yet
- Only very simple mouse event (click and move) handling is implemented
- complicated (e.g., drag & drop, keyboard stroke & mouse event combination, etc) events are not supported yet
- double click may not work