http/3 protocol support

[macbre]

• nginx server with http/3 support (listening on port 9001)
• integration tests entry
• fix mainDomainHttpProtocol metric as h/3 is used by subsequent requests for the same domain

$ node examples/index.js https://gf.dev/http3-test
phantomas v2.2.0 loaded from /Users/macbre/git/phantomas
Opening <https://gf.dev/http3-test> ...
Response: GET https://gf.dev/http3-test [text/html h2]
Response: GET https://gf.dev/cdn-cgi/apps/head/BbOSJ-ZMRnT-WKwVXSLwrT5XQss.js [application/javascript h2]
Response: GET https://gf.dev/static/css/all.min.css [text/css h2]
Response: GET https://gf.dev/static/images/sections/footer/logo-desktop.svg [image/svg+xml h3-29]
Response: GET https://gf.dev/cdn-cgi/bm/cv/669835187/api.js [text/javascript h3-29]
Response: GET https://gf.dev/static/fonts/geekflare-icons.woff [font/woff h3-29]
...

See #929

[macbre]

Tests do not pass with Chromium 90.0.4430.93 😞

Works locally with Chromium 91:

  mainDomainHttpProtocol: 'h3-29',
  oldHttpProtocol: 0,
  mainDomainTlsProtocol: 'QUIC',
  oldTlsProtocol: 0,