Remove unfollowed assets from Libraries

[jaedb]

When unfollowing an asset (playlist, artist or album), we need to remove it from the appropriate library. Because we store the library uris for re-use later, if we unfollow an asset it will still appear in your library.

Also look to add a Refresh button to allow manual re-fetching of libraries. This will be necessary when users are managing their library outside of Iris.

[jaedb]

In Library status detected by a URI's presence in the ui.library_{asset} array. When checking an item's library status, if in library, we add it to this array. This means there is no way of checking if we've loaded our first batch of records (on load of said Library page).

1. Detect and remove duplicates in library indexes
2. Detect whether we have actively loaded a library, or if it's populated consequentially. This will decide whether on load of Library page, we fetch the first batch or not.
3. Add Follow/Unfollow to relevant context menus. On show of context menu, we may need to call Spotify to fetch follow status. Confirm authorized status first.

[jaedb]

Ready for the next release