RFR: 8351565: Implement JEP 502: Stable Values (Preview) [v43]

[Per Minborg]

> Implement JEP 502.
> 
> The PR passes tier1-tier3 tests.

Per Minborg has updated the pull request incrementally with one additional commit since the last revision:

  Fix doc issue with NULL_SENTINEL

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/23972/files
  - new: https://git.openjdk.org/jdk/pull/23972/files/f1d96441..365d9468

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=23972&range=42
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=23972&range=41-42

  Stats: 8 lines in 1 file changed: 4 ins; 3 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/23972.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/23972/head:pull/23972

PR: https://git.openjdk.org/jdk/pull/23972