Add unique hover/select samples to settings sidebar buttons

osu.Game/Graphics/UserInterface/HoverSampleSet.cs

@@ -15,6 +15,9 @@ namespace osu.Game.Graphics.UserInterface
         [Description("button")]
         Button,
 
+        [Description("button-sidebar")]
+        ButtonSidebar,
+
         [Description("toolbar")]
         Toolbar,
 

osu.Game/Overlays/Settings/SidebarButton.cs

@@ -16,6 +16,11 @@ namespace osu.Game.Overlays.Settings
         [Resolved]
         protected OverlayColourProvider ColourProvider { get; private set; }
 
+        protected SidebarButton()
+            : base(HoverSampleSet.ButtonSidebar)
+        {
+        }
+
         [BackgroundDependencyLoader]
         private void load()
         {