[Feature Request] MPD support

[slendidev]

It would be very cool if there were MPD support similar to MPRIS, which would allow not only for song information, but also things like crossfade control, output control and other features MPD-specific.

[slendidev]

If it's of any use, I mega vibe slopped a quick POC which seems to work quite well: https://github.com/slendidev/quickshell/tree/master/src/services/mpd