Use SDL3 screen saver functions to implement AllowScreenSuspension

This removes the custom Android and iOS implementations, and also adds support for desktop platforms.

osu.Framework.iOS/IOSGameHost.cs

@@ -30,15 +30,6 @@ namespace osu.Framework.iOS
 
         protected override IWindow CreateWindow(GraphicsSurfaceType preferredSurface) => new IOSWindow(preferredSurface, Options.FriendlyGameName);
 
-        protected override void SetupForRun()
-        {
-            base.SetupForRun();
-
-            AllowScreenSuspension.Result.BindValueChanged(allow =>
-                    InputThread.Scheduler.Add(() => UIApplication.SharedApplication.IdleTimerDisabled = !allow.NewValue),
-                true);
-        }
-
         protected override void SetupConfig(IDictionary<FrameworkSetting, object> defaultOverrides)
         {
             if (!defaultOverrides.ContainsKey(FrameworkSetting.ExecutionMode))