feat: Adds an Item/Mobile memory leak detector. Fixes minor leak in doors. (#2159)

### Summary

Adds the command [TrackLeaks to enable tracking item/mobiles that have been deleted but still have dangling references. Requires adding the _TRACK_LEAKS_ define constant during build.

Projects/Server/World/World.cs

@@ -492,7 +492,12 @@ public static class World
         else
         {
             logger.Warning($"Attempted to call World.RemoveEntity with '{entity.GetType()}'. Must be a mobile or item.");
+            return;
         }
+
+#if TRACK_LEAKS
+        EntityFinalizationTracker.TrackEntity(entity);
+#endif
     }
 
     [MethodImpl(MethodImplOptions.AggressiveInlining)]