Move song select touch detector to solo implementation

It should not run in multiplayer. Even if we wanted to allow touch-only
playlist items at some point, the current behaviour of multiplayer song
selects with respect to touch device mod is currently just broken.

osu.Game/Screens/Select/PlaySongSelect.cs

@@ -48,6 +48,8 @@ namespace osu.Game.Screens.Select
         private void load(OsuColour colours)
         {
             BeatmapOptions.AddButton(ButtonSystemStrings.Edit.ToSentence(), @"beatmap", FontAwesome.Solid.PencilAlt, colours.Yellow, () => Edit());
+
+            AddInternal(new SongSelectTouchInputDetector());
         }
 
         protected void PresentScore(ScoreInfo score) =>

osu.Game/Screens/Select/SongSelect.cs

@@ -279,7 +279,6 @@ namespace osu.Game.Screens.Select
                 {
                     RelativeSizeAxes = Axes.Both,
                 },
-                new SongSelectTouchInputDetector()
             });
 
             if (ShowFooter)