Add missing screen level mod application settings for some screens

Closes #7480. But based on discussion in there this solution may change.

osu.Game/Overlays/Settings/Sections/Maintenance/DirectorySelectScreen.cs

@@ -24,6 +24,8 @@ namespace osu.Game.Overlays.Settings.Sections.Maintenance
 
         private OsuDirectorySelector directorySelector;
 
+        public override bool AllowTrackAdjustments => false;
+
         /// <summary>
         /// Text to display in the header to inform the user of what they are selecting.
         /// </summary>

osu.Game/Screens/Import/FileImportScreen.cs

@@ -23,6 +23,8 @@ namespace osu.Game.Screens.Import
     {
         public override bool HideOverlaysOnEnter => true;
 
+        public override bool AllowTrackAdjustments => false;
+
         private OsuFileSelector fileSelector;
         private Container contentContainer;
         private TextFlowContainer currentFileText;

osu.Game/Screens/OnlinePlay/OnlinePlayScreen.cs

@@ -24,6 +24,8 @@ namespace osu.Game.Screens.OnlinePlay
         [Cached]
         protected readonly OverlayColourProvider ColourProvider = new OverlayColourProvider(OverlayColourScheme.Plum);
 
+        public override bool AllowTrackAdjustments => false;
+
         public override bool CursorVisible => (screenStack?.CurrentScreen as IOnlinePlaySubScreen)?.CursorVisible ?? true;
 
         // this is required due to PlayerLoader eventually being pushed to the main stack