mappable "push to mute" button for new video calls

[dull-kiwi]

Add a mappable 'push-to-mute' button for the new video rooms. This would mute the user in the call for as long as they held the button. Once the button is released they would become unmuted again.

This may seem niche but it's a great quality of life feature missing from element (and other matrix clients) preventing my friends from switching over.

The main use case is for playing games while on a matrix call, you may want to occasionally talk 'in-game' using a 'push-to-talk' button in-game. Mapping a 'push-to-mute' function to the SAME button in element avoids the user being heard by other call participants twice - once in the call, and once in game (which never really sync up making it difficult to understand them and sometimes quite irritating to listen to).