samba-tool: Add domain member leave

Signed-off-by: David Mulder <dmulder@suse.com>
Reviewed-by: Rowland Penny <rpenny@samba.org>

Autobuild-User(master): David Mulder <dmulder@samba.org>
Autobuild-Date(master): Thu Nov  4 20:43:32 UTC 2021 on sn-devel-184
