s3:winbindd: use wb_sids2xids instead of wb_sid2gid in winbindd_sid_to_gid

s3:winbindd: use wb_sids2xids instead of wb_sid2gid in winbindd_sid_to_gid

The main purpose of the change is to hand the sid into the
idmap backend and handle responsiblity for handling the
sid-type correctly to the idmap backend instead of failing
directly when the sid is not of group type.

Hence backends like rid who are sid-type agnostic, can
return gids also for sids of other types. This is an important
fix to make sid_to_gid behave the consistently with and without
the presence of cache entries.

We need to additionally filter the result for id type GID
or more general (BOTH) to keep the behaviour.

This is a step towards using only one codepath to id_mapping.

Signed-off-by: Michael Adam <obnox@samba.org>
Reviewed-by: Stefan Metzmacher <metze@samba.org>