Add HTTP/3 Support to zTunnel

[stevenctl]

HTTP/3 and QUIC may have benefits for TCP proxying, and are required before we can implement #148.

The first step is choosing a lib. For now, looking at https://github.com/hyperium/h3. Seems that support in https://github.com/hyperium/hyper is further off.

See this doc for more info.

• [ ] Implement CONNECT in h3 lib
• [ ] Design for how to expose h2 vs h3
• [ ] Abstract some of the HTTP code in zTunnel to allow bringing in the lib
• [ ] Add h3 support properly

[PiotrSikora]

HTTP/3 and QUIC may have benefits for TCP proxying, and are required before we can implement #148.

They are not strictly required for it, since you can proxy UDP over HTTP/2 without dropping any packets.

Also, this seems like a duplicate of https://github.com/istio/ztunnel/issues/150?