added new methods to database

- added methods `songsInLibraryArtistsFiltered`, `songsInAllFollowedArtistsFiltered` to db and related changes - allow to play only songs from artists that are visible - added possibility to play songs from library artists - show as number of items the number of visible items like on songs tab (in `HomeArtists` and also `HomeAlbums`, `HomeLibrary`)