fix: Prepares for IPooledEnumerable removal (#1548)

### Summary

- Removes `IPooledEnumerable` (non-generic)
- Changes `IPooledEnumerable<T>` so that  `Free()` is replaced with the `IDisposable` pattern

Projects/UOContent/Items/Containers/MarkContainer.cs

@@ -136,12 +136,9 @@ public partial class MarkContainer : LockableContainer
         {
             if (item.Z == p.Z)
             {
-                eable.Free();
                 return true;
             }
         }
-
-        eable.Free();
         return false;
     }