Support Samba 4.9
    
    Samba 4.9 became a bit more strict about creating a local NT token and a
    failure to resolve or create BUILTIN\Guests group will cause a rejection
    of the connection for a successfully authenticated one.
    
    Add a default mapping of the nobody group to BUILTIN\Guests.
    
    BUILTIN\Guests is a special group SID that is added to the NT token for
    authenticated users.
    
    For real guests there is 'guest account' option in smb.conf which
    defaults to 'nobody' user.
    
    This was implicit behavior before as 'guest account = nobody' by
    default would pick up 'nobody' group as well.
    
    Fixes: https://pagure.io/freeipa/issue/7705
    Reviewed-By: Rob Crittenden <rcritten@redhat.com>
    (cherry picked from commit 703497532abe4189835d0a02b32f9919c889bc1c)
    
    Reviewed-By: Christian Heimes <cheimes@redhat.com>