RFR: 8321223: Implementation of Scoped Values (Second Preview)

[Alan Bateman]

This API is sitting out JDK 22, meaning no API/implementation changes in this PR. Some small API changes are likely for JDK 23.

For now, we just need to bump JEP number/title that shows up in the preview section of the javadoc.

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Commit messages:
 - Initial commit

Changes: https://git.openjdk.org/jdk/pull/16937/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=16937&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8321223
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/16937.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16937/head:pull/16937

PR: https://git.openjdk.org/jdk/pull/16937