Flash overlay rework and bugfixes (#27369)

Content.Shared/Flash/Components/FlashedComponent.cs

@@ -0,0 +1,9 @@
+using Robust.Shared.GameStates;
+
+namespace Content.Shared.Flash.Components;
+
+/// <summary>
+///     Exists for use as a status effect. Adds a shader to the client that obstructs vision.
+/// </summary>
+[RegisterComponent, NetworkedComponent]
+public sealed partial class FlashedComponent : Component { }