QUIC: added ALPN checks. quic-transport draft 29: section 7: * authenticated negotiation of an application protocol (TLS uses ALPN [RFC7301] for this purpose) ... Endpoints MUST explicitly negotiate an application protocol. This avoids situations where there is a disagreement about the protocol that is in use. section 8.1: When using ALPN, endpoints MUST immediately close a connection (see Section 10.3 of [QUIC-TRANSPORT]) with a no_application_protocol TLS alert (QUIC error code 0x178; see Section 4.10) if an application protocol is not negotiated. Changes in ngx_quic_close_quic() function are required to avoid attempts to generated and send packets without proper keys, what happens in case of failed ALPN check.