Get rid of the OverlayEffectsComponent stuff (#3010)

* Get rid of the OverlayEffectsComponent stuff because it just ended up creating workarounds for it's bugs, without removing any functionality

* Flashes and Flashbangs use the same code now (the Flashable path because it's better)

Content.Shared/Interfaces/IConfigurableOverlay.cs

@@ -1,9 +0,0 @@
-using Content.Shared.GameObjects.Components.Mobs;
-
-namespace Content.Shared.Interfaces
-{
-    public interface IConfigurableOverlay
-    {
-        void Configure(OverlayParameter parameter);
-    }
-}