Add ability to use HM as only a media player device

[dinki]

HassMic offers, by far, the best media_player device for View Assist use. Recently I have switched my mic input to Wyoming as to take advantage of on device wakeword to lighten the load on my wifi.

This is a request to allow the user to be able to use HassMic as only a media player device and not use the microphone side of things. Perhaps some would also like a toggle that would allow it to only be used as a microphone device.

Thanks for all you do Jeff! I'm excited to see the other improvements you have in store for us!