Background Segmentation MASK spec PR.

Hi WebRTC members,

We debated the use of Video Frames with Elad and Jan-Ivar and now we changed it to ImageBitmap https://github.com/w3c/mediacapture-extensions/pull/142#issuecomment-2152336794.

As suggested by Jan-Ivar, we also put up an issue in the WebCodecs repo to discuss VideoFrame Metadata Registry https://github.com/w3c/webcodecs/issues/800


PTAL and let us know if you have any suggestions.

-Riju.