Properly handle redundant MediaSession play/pause requests

MediaSession pause requests may happen even when Funkwhale is already in a
paused state. Previously FW would flip between play/pause without
consideration for the current state instead of doing nothing when
the playback state matches the requested one.

Notably, this made Funkwhale resume audio playback when entering sleep mode
on my system.
6 jobs for fix_resume_on_sleep in 12 minutes and 43 seconds (queued for 3 seconds)