krb5pac.idl: introduce PAC_DOMAIN_GROUP_MEMBERSHIP to handle the resource groups

Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>

Autobuild-User(master): Andrew Bartlett <abartlet@samba.org>
Autobuild-Date(master): Thu Jun 30 07:16:45 CEST 2016 on sn-devel-144
