Add support for HTTP Datagrams (RFC 9297)

[1511563371]

I want to use lsquic as the server and quic-go as the client.
However, quic-go supports HTTP/3 (RFC 9114), including QPACK (RFC 9204) and HTTP Datagrams (RFC 9297). However, in lsquic, I did not see HTTP Datagrams (RFC 9297).

[1511563371]

Second Question:
Is linux's io_uring currently supported ?

[dtikhonov]

lsquic does not yet support RFC 9297.

The two implementations, quic-go and lsquic, are interoperable. I am curious: what is your use case for the HTTP/3 datagrams?

lsquic is "bring your own networking:" The library provides you enough callbacks for you to hook it into io_uring, or whatever other mechanism.

[dtikhonov]

@1511563371, a proposed implementation now exists as PR #614. Please have a look at the APIs and provide comments.