RFR: 8273042: TLS Certificate Compression

[Xue-Lei Andrew Fan]

Hi,

Please review the implementation of RFC 8879, TLS Certificate Compression, in JDK.  The TLS Certificate Compression standard is an essential part for QUIC connections and performance improvement for TLS connections.  More details, please refer to the [JEP](https://bugs.openjdk.java.net/browse/JDK-8281710) proposal.

The JEP was submitted, and it may take time for the final approval.  But let me know you ideas and concerns about the proposal and implementation.

JEP: https://bugs.openjdk.java.net/browse/JDK-8281710

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Commit messages:
 - Merge
 - Describe public APIs
 - test and httpclient
 - 8273042: TLS Certificate Compression
 - Merge
 - Merge
 - Merge
 - 8273042: TLS Certificate Compression

Changes: https://git.openjdk.java.net/jdk/pull/7599/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=7599&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8273042
  Stats: 1822 lines in 17 files changed: 1796 ins; 16 del; 10 mod
  Patch: https://git.openjdk.java.net/jdk/pull/7599.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/7599/head:pull/7599

PR: https://git.openjdk.java.net/jdk/pull/7599