7904141: JTReg should support running compact source files

[sormuras]

Please review this change that adds support for running JEP 512: Compact Source Files and Instance Main Methods as jtreg main tests.

This pull request also adds JDK 25 to the GHA-based CI workflow and updates to use newer GitHub actions: actions/checkout@v6 and actions/setup-java@v5

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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

Issue

• CODETOOLS-7904141: JTReg should support running compact source files (Enhancement - P3)

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/jtreg.git pull/313/head:pull/313
$ git checkout pull/313

Update a local copy of the PR:
$ git checkout pull/313
$ git pull https://git.openjdk.org/jtreg.git pull/313/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 313

View PR using the GUI difftool:
$ git pr show -t 313

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/jtreg/pull/313.diff

Using Webrev

Link to Webrev Comment

[bridgekeeper]

👋 Welcome back cstein! 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.

[mlbridge]

Webrevs

• 01: Full - Incremental (d362d93c)
• 00: Full (f4f5e00d)