RFR: 8355022: Implement JEP 506: Scoped Values [v2]

[Andrew Haley]

> Propose to finalize scoped values.
> The only functional change is that the orElse() method no longer accepts a null argument.

Andrew Haley has updated the pull request incrementally with one additional commit since the last revision:

  ScopedValue::orElse() does not accept null as an argument.

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Changes:
  - all: https://git.openjdk.org/jdk/pull/24923/files
  - new: https://git.openjdk.org/jdk/pull/24923/files/b4d77672..00ded12f

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=24923&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=24923&range=00-01

  Stats: 5 lines in 1 file changed: 2 ins; 3 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/24923.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/24923/head:pull/24923

PR: https://git.openjdk.org/jdk/pull/24923