Core/Movement: Get zone/area IDs from vmap data in the liquid update

Port From (https://github.com/TrinityCore/TrinityCore/commit/51ce3b1c1dc6a53938ed6f240bac00681d18a44f)

Source/Game/Collision/Maps/MapTree.cs

@@ -30,6 +30,7 @@ namespace Game.Collision
             ground_Z = float.NegativeInfinity;
         }
 
+        public int rootId;
         public ModelInstance hitInstance;
         public GroupModel hitModel;
         public float ground_Z;