Optimise flashlights (#2468)

Flashlights were calling dirty EVERY TICK so this just means they only call it when absoluetely necessary which saves a lot.

Co-authored-by: Metal Gear Sloth <metalgearsloth@gmail.com>

Content.Shared/GameObjects/Components/Power/SharedPowerCell.cs

@@ -3,6 +3,11 @@ using Robust.Shared.Serialization;
 
 namespace Content.Shared.GameObjects.Components.Power
 {
+    public static class SharedPowerCell
+    {
+        public const int PowerCellVisualsLevels = 4;
+    }
+
     [Serializable, NetSerializable]
     public enum PowerCellVisuals
     {