Jetty Transport: Support HTTP/3

[kwin]

New feature, improvement proposal

Support connections via HTTP/3. Supported in Jetty as outlined in https://jetty.org/docs/jetty/12.1/programming-guide/client/http.html#transport-http3.

FTR: JDK HTTP Client supports HTTP/3 with Java 26+ (https://inside.java/2025/10/22/http3-support/).

[kwin]

This is not yet supported by Maven Central: https://http3.net/?url=https%3A//repo1.maven.org/maven2/ but by Google's Mirror: https://http3.net/?url=https%3A//maven-central-eu.storage-download.googleapis.com/maven2/.