RFR: 8366364: Return enabled signature schemes with SSLConfiguration#getSSLParameters() call [v6]

[Artur Barashev]

> For the signatureSchemes we return only what's been set by the user, the default values are not being returned like for other SSLParameters.
> Also enhancing "java -XshowSettings:security:tls" option to show the enabled signature schemes.

Artur Barashev has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains seven additional commits since the last revision:

 - Adding a unit test
 - Merge branch 'master' into JDK-8366364
 - Revert NamedGroup constraints filtering
 - - Use better logging method
   - Remove now unnecessary null check for config.signatureSchemes
 - Log unavailable configured signature scheme
 - Adjust formatting
 - 8366364: Address inconsistencies in SSLParameters object returned by SSLConfiguration#getSSLParameters() call

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/27961/files
  - new: https://git.openjdk.org/jdk/pull/27961/files/f7052e03..ef4877b9

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=27961&range=05
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=27961&range=04-05

  Stats: 19225 lines in 530 files changed: 12062 ins; 4716 del; 2447 mod
  Patch: https://git.openjdk.org/jdk/pull/27961.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27961/head:pull/27961

PR: https://git.openjdk.org/jdk/pull/27961