It seems we can get into a Phonon pause state without going through
JuK's own pause-specific code path. With this patch I can watch KMix
receive pause events on MPRIS2 with phonon-vlc.

Based on a patch by James Smith that has been languishing in a review
request. My apologies for the delay! Some whitespace fixes as well.

If there's an open Juk bug for this please let me know and I'll review
it. I'm closing/CC-ing the one bug I see that might be relevant, which
couldn't be reproduced earlier (and shouldn't be reproduceable after
this change).

REVIEW:118754
BUG:290689