MediaCollectionsTileService throws on empty playlist

[fstanis]

These lines rely on a few things being non-empty:

horologist/media-sample/src/main/java/com/google/android/horologist/mediasample/data/service/tile/MediaCollectionsTileService.kt

Lines 72 to 78 in de6e198

	val playlists = playlistRepository.getAll()
	.first()
	val firstPlaylist = playlists.first()
	val firstSong = firstPlaylist.mediaList.first()
	val lastPlaylist = playlists.last()

If that's not true, the tile throws Caused by: java.util.NoSuchElementException: List is empty.

We need to add a default "empty playlist" tile.

[yschimke]

If we are changing this, we might want to consider adding an empty sign-in state also. Once you signin or mark guest mode, we serve the content.

[yschimke]

cc @kul3r4