refactor for async dao

[pca006132]

Depends on #267. I split the changes into commits, so it should be slightly simpler to read. That said, I am not sure if the commits are independently compilable. I did not spend time on that.

This is mainly for the async dao, which should improve download performance; at least things should not crash. That said, I also changed things like the API for downloading songs, since I noticed a lot of duplication there.

Note that I haven't yet tested this much, cuz this is rebased from elsewhere. Will need some time to do that.

Also, AutomotiveRepository is not fixed. I don't see an easy way to make this async:

tempus/app/src/tempus/java/com/cappielloantonio/tempo/service/MediaLibraryServiceCallback.kt

Lines 364 to 374 in 6698052

	override fun onAddMediaItems(
	mediaSession: MediaSession,
	controller: MediaSession.ControllerInfo,
	mediaItems: List<MediaItem>
	): ListenableFuture<List<MediaItem>> {
	return super.onAddMediaItems(
	mediaSession,
	controller,
	MediaBrowserTree.getItems(mediaItems)
	)
	}

[eddyizm]

I had to revert the dependency, it caused significant issues with the play queue. I suggest we roll that one in smaller chunks and only add here what has or can be tested - we can create a test branch and build an apk to gets users to run a debug version.

[pca006132]

I don't have time recently for that. Maybe I can point out the pieces of code related to shuffling in the previous PR and you can try to do that.

[eddyizm]

Hi @pca006132 ,
Totally understand. Sure thing, if you can do that< i can will poke around at it and try to test a little more thoroughly on my end and get those changes back in as I do feel they are needed.