extdom: user getorigby{user|group}name if available
    
    New calls, getorigbyusername() and getorigbygroupname(), are added to
    libsss_nss_idmap. They allow to query the AD specific attributes for a
    user or a group directly. Besides a minor performance benefit it helps
    to avoid issues if there are users and groups with the same name and the
    group is not a user-private group but a real group with members.
    
    Fixes: https://pagure.io/freeipa/issue/9127
    Reviewed-By: Alexander Bokovoy <abokovoy@redhat.com>