Simple speedtest server and client using webtransport over HTTP/3

./server-speedtest-webtransport-go -h
Usage of ./server-speedtest-webtransport-go:
  -addr string
        address:port to listen on (default ":4443")
  -cert string
        path to the certificate (default "cert.pem")
  -hostname string
        server hostname (default "localhost")
  -key string
        path to the private key (default "key.pem")
  -www string
        HTTP root directory (default "www")

The server handles webtransport sessions on these two endpoints:

• /ndt/vquic/download: sends data on a single stream during 10 seconds, receives final stats on another one
• /ndt/vquic/upload: waits for data on a single stream for 10 seconds, sends final stats on another one

A successful execution of a test on an endpoint produces a result in the following format:

{
    "TransferKind": 0, // 0 => Client download, 1 => Client upload
    "BytesReceived": 914620416,
    "StartTime": "2022-12-13T13:20:19.611522162+01:00", // RFC 3339 format
    "ElapsedTime": 10743504  // µs
}

Each test result is printed on stdout.

www/index.html contains a simple webpage triggering the download and upload tests. It displays the obtained bandwidth. The ?target= search parameter allows setting the speedtest server hostname when it differs from the current hostname.