CVE-2023-4154 libcli/security: prepare security_descriptor_acl_add() to place the...

CVE-2023-4154 libcli/security: prepare security_descriptor_acl_add() to place the ace at a position

Often it is important to insert an ace at a specific position in the
ACL. As a default we still append by default by using -1, which is the
generic version of passing the number of existing aces.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=15424

Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
Reviewed-by: Douglas Bagnall <douglas.bagnall@catalyst.net.nz>
(cherry picked from commit c3cb915a67aff6739b72b86d7d139609df309ada)