Partially-marshalled query response; that is, it has been uncompacted from
the compact [root:Trie] representation, but not yet rendered into a [root: Cstruct].buf.
response_of_answer query answer is the Packet.t constructed
from the answer to the query
response_of_answer query answer
answer_of_response response is the answer corresponding
to the upstream response for proxied or forwarded response.
Answer a query about [root:domain_name], given a query type [root:q_type] and a
[root:Trie] of DNS data.
Answer one or more [root:questions] given a [root:Trie] of DNS data.
create ~id q_class q_type q_name creates a query for q_name with the
supplied id, q_class, and q_type.
create ~id q_class q_type q_name