Companion app as media_player entity

**Is your feature request related to a problem? Please describe.**

No

**Describe the solution you'd like**

I would like to be able to "cast" media to the Home Assistant companion app on Android so I can play cloud TTS messages (from Nabu Casa or Google TTS) instead of just the "built-in" TTS that sounds very robotic. This could also serve as a media player for other audio as well.

**Describe alternatives you've considered, if any**

browser_mod which I can't seem to get working, is clunky, and has limitations and awkward workarounds.

**Additional context**