Fix duplicate entries in TBoldObjectList.InternalAddNew

[bero]

Problem

When using TBoldNavigator's Insert button on a list handle bound to an allInstances expression (e.g., Project.allInstances), newly created objects appeared twice in the grid.

Cause

InternalAddNew calls CreateNew, which automatically registers the object in the system's class extent. It then calls ObjectListController.AddLocator directly, bypassing the duplicate prevention logic in TBoldObjectList.AddLocator.

For allInstances lists, this results in the same object being added twice.

Solution

Check if the object's locator already exists in the list before adding new in InternalAddNew