resolved: fully follow CNAMEs in the DNS stub after all

resolved: fully follow CNAMEs in the DNS stub after all

In 2f4d8e577ca7bc51fb054b8c2c8dd57c2e188a41 I argued that following
CNAMEs in the stub is not necessary anymore. However, I think it' better
to revert to the status quo ante and follow it after all, given it is
easy for us and makes sure our D-Bus/varlink replies are more similar to
our DNS stub replies that way, and we save clients potential roundtrips.

Hence, whenever we hit a CNAME/DNAME redirect, let's restart the query
like we do for the D-Bus/Varlink case, and collect replies as we go.