quic: http/3 datagrams partially diverge from spec

Http datagrams are according to spec composed as:

HTTP/3 Datagram {
  Quarter Stream ID (i),
  HTTP Datagram Payload (..),
}

and beside this a normal quic datagram.
If I understand the current implementation correctly, the quarter stream id of the bidirectional stream is not included,
and just unfiltered quicdatagrams are sent.
Of course, it is not difficult to sort this issue out on js side, but may be users may stumble upon this.
@jasnell @pimterry what do you think?

Implementing this would not be really hard.

L’issue n’indique ni fichier ni test. Commence par localiser l’implémentation des datagrammes QUIC et HTTP/3 de Node.js, puis compare son framing avec la structure HTTP/3 Datagram citée ici. Le travail est terminé lorsque les datagrammes bidirectionnels incluent la quarter stream ID, tandis que les datagrammes QUIC ordinaires restent distincts ; exécute les tests existants pertinents après les avoir localisés.