Flash overlay rework and bugfixes (#27369)

Content.Shared/Flash/SharedFlashSystem.cs

@@ -1,19 +1,10 @@
-using Robust.Shared.GameStates;
+using Content.Shared.StatusEffect;
 
 namespace Content.Shared.Flash
 {
     public abstract class SharedFlashSystem : EntitySystem
     {
-        public override void Initialize()
-        {
-            base.Initialize();
-
-            SubscribeLocalEvent<FlashableComponent, ComponentGetState>(OnFlashableGetState);
-        }
-
-        private static void OnFlashableGetState(EntityUid uid, FlashableComponent component, ref ComponentGetState args)
-        {
-            args.State = new FlashableComponentState(component.Duration, component.LastFlash);
-        }
+        [ValidatePrototypeId<StatusEffectPrototype>]
+        public const string FlashedKey = "Flashed";
     }
 }