macosx: Reload audio data source more cleanly, only when needed

The way the audio data source refreshes its data and views at the moment is a bit janky and often relies on brute-forcing by replacing the displayed collection array over and over again, leading to refreshing the collection view data and layout over and over again. This is inefficient and leads to things like album art flashing in collection views when it shouldn't (such as when a new song is set to play).

This PR includes changes that reset data and layouts only when it is needed, cutting down on most of the resetting that was previously going on.

Signed-off-by: Claudio Cambra claudio.cambra@gmail.com