Improve ECH checking

[AAGiron]

Currently, checking for ECH support happens by looking only at the capture file. We could improve this, by observing not only if the handshake used ECH but also if the server support ECH in DNS records. Maybe checking for ECH/GREASE at the client side (if possible, or something else to find client support).

Therefore this analyzer could help to diagnose if the handshake used ECH and, if not, check if the server supports it. A good starting point is here.