tls_handshakes: add endpoint addresses to handshake list (#711)

* tls_handshakes: add IP addresses

* tls_handshakes: extract ip from tcp-connect

* tls_handshake: switched to trace event

* saver.go: get remoteAddr before handshake

Not sure whether this is strictly necessary, but I'd rather take the
remoteAddr before calling Handshake, just in case a future version
of the handshake closes the `conn`. In such a case, `conn.RemoteAddr`
would return `nil` and we would crash here.

This occurred to me while reading once again the diff before merging.

Co-authored-by: decfox <decfox>
Co-authored-by: Simone Basso <bassosimone@gmail.com>

internal/model/archival.go

@@ -163,6 +163,7 @@ type ArchivalTCPConnectStatus struct {
 //
 // See https://github.com/ooni/spec/blob/master/data-formats/df-006-tlshandshake.md
 type ArchivalTLSOrQUICHandshakeResult struct {
+	Address            string                    `json:"address"`
 	CipherSuite        string                    `json:"cipher_suite"`
 	Failure            *string                   `json:"failure"`
 	NegotiatedProtocol string                    `json:"negotiated_protocol"`