Define HTTP/3 Error Type

[flano-yuki]

I know that the HTTP/3 specification and implementations are under development. HTTP/3 and QUIC error types are not yet defined in the NEL specification.

It may be too early now, but I think defining HTTP/3 and QUIC error types (group) is useful for deploying it.

for instance, Chrome sends a report of h3.protocol.error when an HTTP/3 connection error occurs. (I understand that it is still experimental.)

{
    "elapsed_time": 4002,
    "method": "GET",
    "phase": "connection",
    "protocol": "http/1.1",
    "sampling_fraction": 1,
    "server_ip": "",
    "status_code": 0,
    "type": "h3.protocol.error",
    "url": "(my-server)"
}

https://cs.chromium.org/chromium/src/net/network_error_logging/network_error_logging_service.cc?l=97