netcmd: silos: silo and auth policy commands use Query class better

netcmd: silos: silo and auth policy commands use Query class better

Since the introduction of the Query class these can be written to be a lot clearer using models.

Signed-off-by: Rob van der Linde <rob@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
Reviewed-by: Douglas Bagnall <douglas.bagnall@catalyst.net.nz>