misc: Migrate Artists page to GridView

Remove custom page implementation for Artists, and instead rely on the
generic `GridView` approach. This also simplifies adding new
sorting/filtering options as next improvements.

The new `ArtistFilter` is a dummy implementation without any real
filters at the moment.

Also, the `go-jellyfin` upgrade is needed to correctly display the album
count for each artist.

ui/controller/controller.go

@@ -206,6 +206,9 @@ func (m *Controller) ConnectArtistGridActions(grid *widgets.GridView) {
 			m.ShowDownloadDialog(tracks, artist.Name)
 		}()
 	}
+	grid.OnShare = func(artistID string) {
+		go m.ShowShareDialog(artistID)
+	}
 }
 
 func (m *Controller) GetArtistTracks(artistID string) []*mediaprovider.Track {