Since the QUIC connection establishment process includes TLS handshake logic,
Connect and TLS handshake are called in the following order:
ConnectStart -> TLSHandshakeStart -> TLSHandshakeDone -> ConnectDone.
Notice: Wait100Continue not implemented as quic-go doesn't support handling
Expect: 100-continue.
* http3: rename RoundTripper to Transport
* http3: rename SingleDestinationRoundTripper to ClientConn
* http3: construct the ClientConn via Transport.NewClientConn
