DNS: show if the response is DNSSEC signed

[Mikaela]

I think it could just be a inconspicious ✔️ somewhere in the output when there is AD flag in the DNS query response (I don't know if the library exposes that though). I don't think unsigned zones or when there is no DNSSEC support should be noted as the majority of domains don't support it.

Edit. http://www.dnspython.org/docs/1.16.0/dns.flags-module.html mentions AD variable, I don't understand page though.