Integrating xwt for WebTransport support

[MOZGIII]

Hey! I'm the author of the https://github.com/MOZGIII/xwt crate (or rather a family of crates). I'd be interested in implementing necessary bits at xwt to allow its use as a backend for renet to enable WebTransport instead of native sockets. WebTransport can be used in both native and wasm environments, making UDP-like networking possible in the browser (without the P2P nature of WebRTC and the complications that come with it).

Would you be interested in implementing support for pluggable network transports for the renet crate?