netcmd: Split 'domain passwordsettings' into a super-command

netcmd: Split 'domain passwordsettings' into a super-command

The show and set options are not really related to each other at all, so
it makes sense to split the code into 2 separate commands.

We also want to add separate sub-commands for PSOs in a subsequent
patch.

Because of the way the sub-command was implemented previously, it meant
that you could specify other command-line options before the 'set' or
'show' keyword, and the command would still be accepted. However, now
that it's a super-command 'set'/'show' needs to be specified before any
additional arguments, so we need to update the test code to reflect
this.

Reviewed-by: Andrew Bartlett <abartlet@samba.org>
Reviewed-by: Garming Sam <garming@catalyst.net.nz>
Signed-off-by: Tim Beale <timbeale@catalyst.net.nz>