Add keyboard shortcuts at song select for mod/random/options.

osu.Game/Screens/Select/PlaySongSelect.cs

@@ -440,8 +440,19 @@ private void promptDelete()
 
         protected override bool OnKeyDown(InputState state, KeyDownEventArgs args)
         {
+            if (args.Repeat) return false;
+
             switch (args.Key)
             {
+                case Key.F1:
+                    modSelect.ToggleVisibility();
+                    return true;
+                case Key.F2:
+                    carousel.SelectRandom();
+                    return true;
+                case Key.F3:
+                    beatmapOptions.ToggleVisibility();
+                    return true;
                 case Key.Enter:
                     footer.StartButton.TriggerClick();
                     return true;