quic: http/3 getting server settings and customSettings

For applications such as webtransport, http settings are important for negotiating capabilities.

The following problems may be present currently:
1.) I do not see a clear API path for a client that connects to a server to get the settings sent by the server.
Looking at the C++ code, I think the available settings could be on the SessionTicket,
However, if I immediately set a callback to onsessionticket after the Promise for QuicSession is fulfilled, I do not see a call.
@jasnell : Is there another API path to get this information? Or is this a bug, if I do not see the callback? Then I will try to make a test.
2.) nghttp3 does not seem to support settings beyond the settings hardcoded in the library. I will query upstream about implementing a mechanism similar to the customSettings mechanism currently used for http2.

Inizia tracciando l’implementazione C++ di QUIC relativa a SessionTicket e onsessionticket, quindi confronta le impostazioni hardcoded di nghttp3 con il meccanismo customSettings di HTTP/2. Conferma il percorso API previsto per le impostazioni del server e definisci test per la consegna dei callback e il supporto alle impostazioni personalizzate; l’issue è completata quando questi comportamenti hanno un’implementazione chiara o una risoluzione upstream.