QUIC: rejected CRYPTO frames received in 1-RTT packets

QUIC: rejected CRYPTO frames received in 1-RTT packets

If a CRYPTO frame was received after the handshake, ngx_quic_handshake()
ran the handshake completion for the second time.  With the check added
in 6f8c520f4, this is limited to short header packets.

Since a client has nothing to send in a CRYPTO frame once the handshake
is complete, such frames are now rejected with the "unexpected_message"
connection error, as does TLS 1.3 for handshake messages received out of
order, and QUIC requires for KeyUpdate.