8355536: Create version constants to model preview language and vm features

[liach]

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.

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Progress

• Change must be properly reviewed (1 review required, with at least 1 Reviewer)
• Change must not contain extraneous whitespace
• Commit message must refer to an issue
• Change requires a CSR request matching fixVersion 25 to be approved (needs to be created)

Issue

• JDK-8355536: Create version constants to model preview language and vm features (Enhancement - P3)(⚠️ The fixVersion in this issue is [26] but the fixVersion in .jcheck/conf is 25, a new backport will be created when this pr is integrated.)

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk.git pull/25017/head:pull/25017
$ git checkout pull/25017

Update a local copy of the PR:
$ git checkout pull/25017
$ git pull https://git.openjdk.org/jdk.git pull/25017/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 25017

View PR using the GUI difftool:
$ git pr show -t 25017

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/jdk/pull/25017.diff

Using Webrev

Link to Webrev Comment

[bridgekeeper]

👋 Welcome back liach! A progress list of the required criteria for merging this PR into master will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

[openjdk]

❗ This change is not yet ready to be integrated.
See the Progress checklist in the description for automated requirements.

[openjdk]

@liach The following labels will be automatically applied to this pull request:

• compiler
• core-libs

When this pull request is ready to be reviewed, an "RFR" email will be sent to the corresponding mailing lists. If you would like to change these labels, use the /label pull request command.

[liach]

Tested tier 1-2, no failure, so this isn't creating breakage. Marking this RFR.

[mlbridge]

Webrevs

• 04: Full (69d941f4)
• 03: Full - Incremental (c1a175ef)
• 02: Full - Incremental (0a3f3896)
• 01: Full (d0ff022f)
• 00: Full (805c6786)

[openjdk]

⚠️ @liach This pull request contains merges that bring in commits not present in the target repository. Since this is not a "merge style" pull request, these changes will be squashed when this pull request in integrated. If this is your intention, then please ignore this message. If you want to preserve the commit structure, you must change the title of this pull request to Merge <project>:<branch> where <project> is the name of another project in the OpenJDK organization (for example Merge jdk:master).

[openjdk-notifier]

The parent pull request that this pull request depends on has now been integrated and the target branch of this pull request has been updated. This means that changes from the dependent pull request can start to show up as belonging to this pull request, which may be confusing for reviewers. To remedy this situation, simply merge the latest changes from the new target branch into this pull request by running commands similar to these in the local repository for your personal fork:

git checkout feature/preview-cffv
git fetch https://git.openjdk.org/jdk.git master
git merge FETCH_HEAD
# if there are conflicts, follow the instructions given by git merge
git commit -m "Merge master"
git push

[openjdk]

@liach this pull request can not be integrated into master due to one or more merge conflicts. To resolve these merge conflicts and update this pull request you can run the following commands in the local repository for your personal fork:

git checkout feature/preview-cffv
git fetch https://git.openjdk.org/jdk.git master
git merge FETCH_HEAD
# resolve conflicts and follow the instructions given by git merge
git commit -m "Merge master"
git push