test_songs: switch top lists to single select mode
test_songs: switch top lists to single select mode

Also created a variable to store dojo.declared extension used by all 3 Lists

maier49/dgrid,dylans/dgrid,kfranqueiro/dgrid,dylans/dgrid,dylans/dgrid,maier49/dgrid,maier49/dgrid,kfranqueiro/dgrid,kfranqueiro/dgrid