RFR: 8355536: Create version constants to model preview language and vm features [v9]

[Chen Liang]

> Sometimes, for version-specific feature access APIs, we wish to access the preview features of the current Java SE release. To reduce the impact of adding one preview-specific version on every site, we can add a constant modeling the preview features as a fake version.

Chen Liang has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 14 commits:

 - Merge branch 'master' of https://github.com/openjdk/jdk into feature/preview-cffv
 - Fixes
 - Fix sourceversion test
 - Merge branch 'master' of https://github.com/openjdk/jdk into feature/preview-cffv
 - Merge branch 'master' of https://github.com/openjdk/jdk into feature/preview-cffv
 - Merge branch 'master' of https://github.com/openjdk/jdk into feature/preview-cffv
 - Merge branch 'master' of https://github.com/openjdk/jdk into feature/preview-cffv
 - Update src/java.base/share/classes/java/lang/reflect/ClassFileFormatVersion.java
 - Update src/java.compiler/share/classes/javax/lang/model/SourceVersion.java
   
   Co-authored-by: Luca Kellermann <lukellmann at gmail.com>
 - Don't need to update latestSupported later
   
 - ... and 4 more: https://git.openjdk.org/jdk/compare/ee3665bc...ce9cf84b

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Changes: https://git.openjdk.org/jdk/pull/25017/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=25017&range=08
  Stats: 1284 lines in 6 files changed: 1138 ins; 87 del; 59 mod
  Patch: https://git.openjdk.org/jdk/pull/25017.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/25017/head:pull/25017

PR: https://git.openjdk.org/jdk/pull/25017