RFR: 8349910: Implement JEP 517: HTTP/3 for the HTTP Client API [v8]

[Daniel Fuchs]

> Hi,
> 
> Please find here a PR for the implementation of [JEP 517: HTTP/3 for the HTTP Client API](https://openjdk.org/jeps/517).
> 
> The CSR can be viewed at [JDK-8350588: Implement JEP 517: HTTP/3 for the HTTP Client API](https://bugs.openjdk.org/browse/JDK-8350588)
> 
> This JEP proposes to enhance the HttpClient implementation to support HTTP/3.
> It adds a non-exposed / non-exported internal implementation of the QUIC protocol based on DatagramChannel and the SunJSSE SSLContext provider.

Daniel Fuchs has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 506 commits:

 - merge latest changes from master branch
 - http3: update H3InsertionsLimitTest to start after receival of client settings
 - merge latest changes from master branch
 - quic: separate out the idle termination timer and the STREAM_DATA_BLOCKED timer
 - quic: simplify idle timeout management
 - http3: rely on the sole isOpen() method instead of isOpen() and isClosed()
 - quic: do not let h3 idle (in pool) timeout to influence the quic transport idle timeout
 - merge latest changes from master branch
 - http3: improve H3ConnectionPoolTest.java
 - Fix snippet
 - ... and 496 more: https://git.openjdk.org/jdk/compare/8d33ea73...d4984d5e

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Changes: https://git.openjdk.org/jdk/pull/24751/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=24751&range=07
  Stats: 103752 lines in 472 files changed: 100891 ins; 1345 del; 1516 mod
  Patch: https://git.openjdk.org/jdk/pull/24751.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/24751/head:pull/24751

PR: https://git.openjdk.org/jdk/pull/24751