Add context versions of wbclient functions

Add context versions of wbclient functions

To make the libwbclient library thread-safe, all functions
that call through to wb_common winbindd_request_response need
to have context that they can use. This commit adds all the
necessary functions.

https://bugzilla.samba.org/show_bug.cgi?id=11149

Signed-off-by: Matthew Newton <matthew-git@newtoncomputing.co.uk>
Reviewed-by: Volker Lendecke <vl@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>
(cherry picked from commit 063c56dba590eec69439eb791a420b40505d4cc0)