Propagating RESET error codes for an unknown stream

[ddragana]

Spec section 4.3:

If a WebTransport implementation intentionally allows only one session over a given HTTP/3 connection, it SHALL forward the error codes within WebTransport application error code range to the application that owns the only session on that connection.

This is the last paragraph of the section, so please read the section for context.

The spec says that if we get a RESET for a stream that is unknown to us (e.g., some steam data have been sent but lost or reordered so that RESET is received before any stream data and therefore we do not know stream type or the session ID) we should propagate the error to the application if HTTP/3 is exclusively used only for a single WebTransport session.

We currently do not propagate this information. This may also need change to neqo-transport.

[ddragana]

I think we should not do this. The benefits of this are low.