perf: regular events to custom events

Engine.Core/Abstract/Assignable/IHasBehaviourController.cs

@@ -8,7 +8,7 @@ public interface IHasBehaviourController : IAssignable
     /// <summary>
     /// Event triggered when the <see cref="IBehaviourController"/> value has has been assigned a new value.
     /// </summary>
-    event BehaviourControllerAssignedEventHandler? OnBehaviourControllerAssigned;
+    Event<IHasBehaviourController> OnBehaviourControllerAssigned { get; }
 
     /// <inheritdoc cref="IBehaviourController" />
     IBehaviourController BehaviourController { get; }