Replaces AnchoredChanged C# event with ComponentMessage (#2905)

* Replaces AnchoredChanged C# event with ComponentMessage

* Removes unneeded fields

Co-authored-by: py01 <pyronetics01@gmail.com>

Content.Server/GameObjects/Components/PA/ParticleAcceleratorPartComponent.cs

@@ -1,8 +1,9 @@
-#nullable enable
+#nullable enable
 using Content.Server.Utility;
 using Robust.Shared.GameObjects;
 using Robust.Shared.GameObjects.Components;
 using Robust.Shared.GameObjects.Components.Transform;
+using Robust.Shared.Interfaces.GameObjects;
 using Robust.Shared.Log;
 using Robust.Shared.ViewVariables;
 
@@ -10,7 +11,6 @@ namespace Content.Server.GameObjects.Components.PA
 {
     public abstract class ParticleAcceleratorPartComponent : Component
     {
-        [ViewVariables] private PhysicsComponent? _collidableComponent;
         [ViewVariables] public ParticleAcceleratorControlBoxComponent? Master;
         [ViewVariables] protected SnapGridComponent? SnapGrid;
 
@@ -18,14 +18,6 @@ namespace Content.Server.GameObjects.Components.PA
         {
             base.Initialize();
             // FIXME: this has to be an entity system, full stop.
-            if (!Owner.TryGetComponent(out _collidableComponent))
-            {
-                Logger.Error("ParticleAcceleratorPartComponent created with no CollidableComponent");
-            }
-            else
-            {
-                _collidableComponent.AnchoredChanged += OnAnchorChanged;
-            }
 
             if (!Owner.TryGetComponent(out SnapGrid))
             {
@@ -33,6 +25,17 @@ namespace Content.Server.GameObjects.Components.PA
             }
         }
 
+        public override void HandleMessage(ComponentMessage message, IComponent? component)
+        {
+            base.HandleMessage(message, component);
+            switch (message)
+            {
+                case AnchoredChangedMessage:
+                    OnAnchorChanged();
+                    break;
+            }
+        }
+
         public void OnAnchorChanged()
         {
             RescanIfPossible();