RFR: 8349910: Implement HTTP/3 for the HTTP Client API [v2]

[Daniel Fuchs]

> Hi,
> 
> Please find here a PR for the implementation of JEP [JDK-8291976: HTTP/3 for the HTTP Client API](https://bugs.openjdk.org/browse/JDK-8291976).
> 
> The CSR can be viewed at [JDK-8350588: Implement 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 409 commits:

 - merge latest changes from master branch
 - http3: add missing <p> separator to Http3DiscoveryMode.ALT_SVC API documentation
 - http3: improve documentation for Http3DiscoveryMode.ALT_SVC
 - http3: Use AlgorithmConstraints and OCSP responses when validating server certificate during QUIC TLS handshake
 - http3: Artur's review - use SecurityUtils.removeFromDisabledTlsAlgs() in test
 - http3: minor improvement to log message
 - http3: Artur's review - remove commented out code from test
 - http3: Artur's review - make methods package private
 - http3: qpack - allow 0 capacity when max capacity is 0
 - Remove flow control from stream limit comments
 - ... and 399 more: https://git.openjdk.org/jdk/compare/1ec64811...4da61bbe

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Changes: https://git.openjdk.org/jdk/pull/24751/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=24751&range=01
  Stats: 102765 lines in 470 files changed: 100142 ins; 1119 del; 1504 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