Add test for thaw dynamic kasp zone

Add test for thaw dynamic kasp zone

Add a test for freezing, manually updating, and then thawing a dynamic
zone with "dnssec-policy". In the kasp system test we add parameters
to the "update_is_signed" check to signal the indicated IP addresses
for the labels "a" and "d". If set to '-', the test is skipped.

After nsupdating the dynamic.kasp zone, we revert the update (with
nsupdate) and update the zone again, but now with the freeze/thaw
approach.