idviews: Restrict anchor to name and name to anchor conversions
    
    When converting the ID override anchor from AD SID representation to
    the object name, we need to properly restrict the type of the object
    that is being resolved.
    
    The same restriction applies for the opposite direction, when
    converting the object name to it's SID.
    
    https://fedorahosted.org/freeipa/ticket/5029
    
    Reviewed-By: Alexander Bokovoy <abokovoy@redhat.com>