Add support for TLS Encrypted Client Hello (ECH)

[Eng-Fouad]

Description

Quoted from Wikipedia:

Encrypted Client Hello (ECH) is a TLS 1.3 protocol extension that enables encryption of the whole Client Hello message, which is sent during the early stage of TLS 1.3 negotiation.[10] ECH encrypts the payload with a public key that the relying party (a web browser) needs to know in advance, which means ECH is most effective with large CDNs known to browser vendors in advance.