feat: added UpdateManager.CallFirstActiveFrameImmediately method for early calls of behaviours

Engine.Core/Systems/UpdateManager.cs

@@ -44,6 +44,17 @@ public class UpdateManager : Behaviour, IEnterUniverse, IExitUniverse
         universe.OnPostUpdate.RemoveListener(OnPostUpdate);
     }
 
+    /// <summary>
+    /// Call the <see cref="IFirstFrameUpdate"/> early if it's in queue to be called by this the <see cref="UpdateManager"/>. 
+    /// It will not be called in the next natural cycle.
+    /// </summary>
+    /// <param name="instance">The instance that will be called now rather than later.</param>
+    public void CallFirstActiveFrameImmediately(IFirstFrameUpdate instance)
+    {
+        if (toCallFirstFrameUpdates.Remove(instance))
+            instance.FirstActiveFrame();
+    }
+
     private void OnFirstUpdate(IUniverse sender, IUniverse.UpdateArguments args)
     {
         for (int i = toCallFirstFrameUpdates.Count - 1; i >= 0; i--)