New return an empty Config suite, use .Add() to add protocol impl.

must be the same with the ALPN nextProto values.

HTTP3 is the ALPN protocol negotiated during the TLS handshake, for QUIC v1 and v2.

HTTP3Draft29 is the ALPN protocol negotiated during the TLS handshake, for QUIC draft 29.

Core is the core interface that promises to be provided for the protocol layer extensions.