Create an HTTP/3 / QUIC sample

[lbussell]

HTTP/3 is fully supported in .NET 7+, but we have no formal samples showing how to enable that scenario. We get issues or questions from time to time about how to enable HTTP/3 in our various images, so we should add a sample for it.

Related

• [HTTP/3] Consider including QUIC dependencies in Docker images #4385
• How to add `libmsquic` to container images #4823

[lbussell]

[Triage] Enabling HTTP/3 is fairly simple if libmsquic is installed. Our samples should focus on installing msquic if we don't decide to include it in our extra images (#4385). If msquic is included in our images somehow, then we should make sure we've documented how to use it in each scenario (distroless, Chiseled, non-extra images, etc.) but a sample may not be necessary.