Media Player Improvements
- Map Media Player volume up, down, mute, next, previous, and play/pause to associated entity defined in your activity's button mapping
- This change makes your media players predicable and allows you to generically control your playing media based on the active activity
- Report Media Player as "on" if associated activity is running
- Always display available entities in Sound Mode dropdown (Activity Media Players) as long as they are not "unavailable"
- Correctly report if media player unmutes