perf!: events refactored throughout all the project to use Event<> class

All delegate events are refactored to use the Event<TSender> and Event<TSender, TArgument> for performance issues regarding delegate events creating garbage, also this gives us better control on event invocation since C# Delegates did also create unnecessary garbage during Delegate.DynamicInvoke

Engine.Core/Abstract/Assignable/IHasEntity.cs

@@ -8,7 +8,7 @@ public interface IHasEntity : IAssignable
     /// <summary>
     /// Event triggered when the <see cref="IEntity"/> value has has been assigned a new value.
     /// </summary>
-    event EntityAssignedEventHandler? OnEntityAssigned;
+    Event<IHasEntity> OnEntityAssigned { get; }
 
     /// <inheritdoc cref="IEntity" />
     IEntity Entity { get; }
@@ -21,6 +21,4 @@ public interface IHasEntity : IAssignable
     /// <see cref="true"/>, if the value given assigned successfully assigned, <see cref="false"/> if not.
     /// </returns>
     bool Assign(IEntity entity);
-
-    delegate void EntityAssignedEventHandler(IHasEntity sender);
 }