RFR: 8349910: Implement JEP 517: HTTP/3 for the HTTP Client API [v10]

[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 545 commits:

 - http3: rename PacketSpaceManager::isAcknowledging to PacketSpaceManager::trackAcknowledgement
 - merge latest changes from master branch
 - http3: fix typo in UniStreamPair.java
 - WriterQueue may leak before the constructor completes
 - Limit the number of retries in H3UserInfoTest
 - Implement IntReader
 - Remove dispatchers field
 - http3: when looking for a connection in the pool, prefer advertised connections for ANY
 - http3: fix Http3PendingConnections::removeCompleted to take into account the case where the Http3Connection was created with an AltService, but we don't have it because the handshake failed
 - Use default timeout in BasicHttp3Test
 - ... and 535 more: https://git.openjdk.org/jdk/compare/5cf349c3...9d67d4a6

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Changes: https://git.openjdk.org/jdk/pull/24751/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=24751&range=09
  Stats: 105147 lines in 470 files changed: 102317 ins; 1335 del; 1495 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