Add Remote Playback API

[ddorwin]

There is a demo at https://avayvod.github.io/remote-playback/test.html.

[Gokula-6sg]

@ddorwin Could you clarify what was planned here? Was the intention to add browser support, a polyfill, or documentation for the Remote Playback API?

[ddorwin]

I believe the intent was to add a button to permission.site that would invoke the API and thus trigger relevant browser UI.

https://crbug.com/41325172#comment21 (not public) was likely the context.