feat(dns): expose more low-level fields (#873)

This pull request started as a draft to enable users to see CNAME answers. It contained several patches which we merged separately (see https://github.com/ooni/probe-cli/pull/873#issuecomment-1222406732 and 2301a30630...60b7d1f87b for details on what has actually changed, which is based on patches originally part of this PR). In its final form, however, this PR only deals with exposing more low-level DNS fields to the archival data format.

Closes: https://github.com/ooni/probe/issues/2228

Related PR spec: https://github.com/ooni/spec/pull/256

internal/model/archival.go

@@ -115,11 +115,15 @@ type ArchivalDNSLookupResult struct {
 	Answers          []ArchivalDNSAnswer `json:"answers"`
 	Engine           string              `json:"engine"`
 	Failure          *string             `json:"failure"`
+	GetaddrinfoError int64               `json:"getaddrinfo_error,omitempty"`
 	Hostname         string              `json:"hostname"`
 	QueryType        string              `json:"query_type"`
+	RawResponse      []byte              `json:"raw_response,omitempty"`
+	Rcode            int64               `json:"rcode,omitempty"`
 	ResolverHostname *string             `json:"resolver_hostname"`
 	ResolverPort     *string             `json:"resolver_port"`
 	ResolverAddress  string              `json:"resolver_address"`
+	T0               float64             `json:"t0"`
 	T                float64             `json:"t"`
 }