passdb: Introduce xid_to_sid

passdb: Introduce xid_to_sid

This explicitly avoids the legacy_[ug]id_to_sid calls, which create
long-term cache entries to S-1-22-x-y if anthing fails. We can't do
this, because this will turn temporary winbind communication failures
into long-term problems: A short hickup in winbind_uid_to_sid will
create a mapping to S-1-22-1-uid for a week. It should be up to the
lower layers to do the caching.

Signed-off-by: Volker Lendecke <vl@samba.org>
Reviewed-by: Christof Schmitt <cs@samba.org>
Bug: https://bugzilla.samba.org/show_bug.cgi?id=13813