RFR: 8371184: Improve jpackage test coverage for "--app-image" option [v2]

[Alexander Matveev]

On Tue, 4 Nov 2025 02:19:41 GMT, Alexey Semenyuk <asemenyuk at openjdk.org> wrote:

>> - Verify that when `--app-image` option is specified, files from the predefined app image are copied verbatim into the output app image (JPackageCommand: add `PREDEFINED_APP_IMAGE_COPY`, update TKit.PathSnapshot class).
>> - Add `LauncherVerifier.launcherDescription()` and use it from LiunuxHelper; extend PropertyFinder class for `LauncherVerifier.launcherDescription()`.
>>  - Automatically reapply verifications to launchers in the predefined app image to the command referencing the predefined app image through `--app-image` option. Other changes relate to this update.
>> 
>> Supplementary:
>> - Clean up redundancies after [8351369: [macos] Use --install-dir option with DMG packaging](https://bugs.openjdk.org/browse/JDK-8351369) fix: remove `JPackageCommand.dmgInstallDir`, simplify InstallDirTest test.
>>  - AppContentTest.java: fix to make test logs stable.
>
> Alexey Semenyuk has updated the pull request incrementally with one additional commit since the last revision:
> 
>   AppContentTest: keep test log stable

Looks good.

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Marked as reviewed by almatvee (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/28118#pullrequestreview-3413923166