Misc replay related changes (#17102)

Content.Client/Gameplay/GameplayState.cs

@@ -13,7 +13,8 @@ using Robust.Shared.Timing;
 
 namespace Content.Client.Gameplay
 {
-    public sealed class GameplayState : GameplayStateBase, IMainViewportState
+    [Virtual]
+    public class GameplayState : GameplayStateBase, IMainViewportState
     {
         [Dependency] private readonly IEyeManager _eyeManager = default!;
         [Dependency] private readonly IOverlayManager _overlayManager = default!;