winbind: Restructure wb_getpwsid

winbind: Restructure wb_getpwsid

This patch moves the responsibility to create a winbind user from the
winbind backends into wb_queryuser.c. The name comes from lsa_lookupsids,
the uid from idmap. If we have a netsamlogon_cache, we get the primary
group sid from there. Without netsamlogon_cache, we default to -513, as
we do right now as default for non-reachable ADS domains anyway. Shell
and homedir default to template. This can all be done in the parent
without contacting any LDAP-related calls and is correct once we have
a netsamlogon_cache.

Once the parent has filled in the userinfo, the idmap child is queried
with the GetNssInfo call, taking the userinfo [in,out]. The child is
free to override the whole thing, something the AD backend will do in
the next patch.

Signed-off-by: Volker Lendecke <vl@samba.org>
Reviewed-by: Uri Simchoni <uri@samba.org>
Reviewed-by: Andreas Schneider <asn@samba.org>