Integrate a Rust (or C FFI) HTTP/3 library with WebTransport draft support

[ctrlaltf2]

[modeco80]

Just to note that using moq-rs (a good idea!) will pretty much all but force Quinn + Axum & Kix's webtransport implementation on top of Quinn (unless we want to have multiple incompatible frameworks/stacks, which doesn't really sound fun.). This is fine since I'm already biased towards axum and was probably going to use it based on familiarity (I've written multiple services with it that either are live or will go live in a while, and I haven't had any major issue with it so far, so..), so /shrug