Use a moved_entities table to record external entities moved to the system source Instead of using a negative eid in the entities table, move the record to a new table so we don't have an interval with a missing eid in entities. Related to #4846892

if not rql('CWConstraintType X WHERE X name "RQLUniqueConstraint"',
           ask_confirm=False):
    rql('INSERT CWConstraintType X: X name "RQLUniqueConstraint"',
        ask_confirm=False)