RFR: Merge jdk20

[Jesper Wilhelmsson]

Forwardport JDK 20 -> JDK 21

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

Commit messages:
 - Merge remote-tracking branch 'jdk20/master' into Merge_jdk20
 - 8301206: Fix issue with LocaleData after JDK-8300719
 - 8300953: ClassDesc::ofInternalName missing @since tag
 - 8300719: JDK 20 RDP2 L10n resource files update

The webrevs contain the adjustments done while merging with regards to each parent branch:
 - master: https://webrevs.openjdk.org/?repo=jdk&pr=12267&range=00.0
 - jdk20: https://webrevs.openjdk.org/?repo=jdk&pr=12267&range=00.1

Changes: https://git.openjdk.org/jdk/pull/12267/files
  Stats: 1078 lines in 85 files changed: 220 ins; 114 del; 744 mod
  Patch: https://git.openjdk.org/jdk/pull/12267.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/12267/head:pull/12267

PR: https://git.openjdk.org/jdk/pull/12267