Make mechanism behaviors properly update, fix eating and drinking (#2472)

* Make mechanisms properly update and fix eating and drinking

* Remove outdated component ignores

* Fix nullable error

* Fix mechanism behavior events

* Remove unnecessary code

Content.Server/GameObjects/Components/Body/Behavior/BrainBehavior.cs

@@ -0,0 +1,62 @@
+#nullable enable
+using Content.Server.GameObjects.Components.Mobs;
+using Content.Shared.GameObjects.Components.Body;
+using Content.Shared.GameObjects.Components.Body.Part;
+using Robust.Shared.GameObjects;
+using Robust.Shared.Interfaces.GameObjects;
+
+namespace Content.Server.GameObjects.Components.Body.Behavior
+{
+    public class BrainBehavior : MechanismBehavior
+    {
+        protected override void OnAddedToBody(IBody body)
+        {
+            base.OnAddedToBody(body);
+
+            HandleMind(body.Owner, Owner);
+        }
+
+        protected override void OnAddedToPart(IBodyPart part)
+        {
+            base.OnAddedToPart(part);
+
+            HandleMind(part.Owner, Owner);
+        }
+
+        protected override void OnAddedToPartInBody(IBody body, IBodyPart part)
+        {
+            base.OnAddedToPartInBody(body, part);
+
+            HandleMind(body.Owner, Owner);
+        }
+
+        protected override void OnRemovedFromBody(IBody old)
+        {
+            base.OnRemovedFromBody(old);
+
+            HandleMind(Part!.Owner, old.Owner);
+        }
+
+        protected override void OnRemovedFromPart(IBodyPart old)
+        {
+            base.OnRemovedFromPart(old);
+
+            HandleMind(Owner, old.Owner);
+        }
+
+        protected override void OnRemovedFromPartInBody(IBody oldBody, IBodyPart oldPart)
+        {
+            base.OnRemovedFromPartInBody(oldBody, oldPart);
+
+            HandleMind(oldBody.Owner, Owner);
+        }
+
+        private void HandleMind(IEntity newEntity, IEntity oldEntity)
+        {
+            newEntity.EnsureComponent<MindComponent>();
+            var oldMind = oldEntity.EnsureComponent<MindComponent>();
+
+            oldMind.Mind?.TransferTo(newEntity);
+        }
+    }
+}