RFR: 8370156: Fix jpackage IconTest [v2]

[Alexey Semenyuk]

On Sat, 18 Oct 2025 02:25:36 GMT, Alexey Semenyuk <asemenyuk at openjdk.org> wrote:

>> Rework IconTest.
>> 
>> Verified it produces the output as expected.
>> 
>> It still will not catch [JDK-8370155](https://bugs.openjdk.org/browse/JDK-8370155). However, this is deliberate to avoid significant changes in the test and implementation in a single commit.
>
> Alexey Semenyuk has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains five commits:
> 
>  - Merge with the master
>  - Merge branch 'master' into JDK-8370156
>  - Rollback JDK-8370100 specific patch
>  - AdditionalLauncher: make getAdditionalLauncherProperties() public; LauncherIconVerifier: make setters unambiguous; Add ConfigurationTarget
>  - IconTest: revamp

@sashamatveev PTAL

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PR Comment: https://git.openjdk.org/jdk/pull/27883#issuecomment-3417798241