quic|http2: implement webtransport capsule protocol support

Beside the quic webtransport wire protocol, there is also the capsule protocol, initially developed for http/2, but know also mentioned in the spec drafts as alternative means of transport for http/3.

As browser support is limited (or not existing), I have also made a draft for webtransport over websocket:
https://datatracker.ietf.org/doc/draft-richter-webtransport-websocket/
that allows to polyfill on the UA side.

Both are implemented in my own package:
https://github.com/fails-components/webtransport/tree/master/main/lib/http2/node
and the polyfill over websocket is successfully tested for a while in my deployment.

I have asked upstream nghttp2, nghttp3, there is currently no plan to implement it.

My plan would to turn my low level code to match a subset of QuicSession, and QuicStream interfaces with regard to webtransport and stream/iter (compare PR for quic https://github.com/nodejs/node/pull/63827) and add it to node.js. (Though I do not know where to place it).

(One side note, I have translated some BSD style licensed code from quiche to js (just two files), I would assume, that this should be ok with node.js licenses or do I need to replace this portion ?).

(And if this becomes important, we can still port hot path to C)

@jasnell @pimterry does this sound like a plan?

Start by reviewing the referenced Node.js QUIC PR and the implementation in main/lib/http2/node from the linked package. Determine where a capsule protocol implementation could fit and how it should match the proposed QuicSession and QuicStream subset. Done means an agreed placement, resolved licensing questions, and working capsule support in Node.js.