IPA: enhance ipa_initgr_get_overrides_send()
    
    This patch makes ipa_initgr_get_overrides_send() public and add support
    to search overrides by UUID or by SID.
    
    Related to https://fedorahosted.org/sssd/ticket/2633
    
    Reviewed-by: Jakub Hrozek <jhrozek@redhat.com>
    (cherry picked from commit 145578006684481434ced78461ab8d1c3570f478)