RFR: 8349504: Support platform-specific JUnit tests in jpackage

[Alexander Matveev]

On Wed, 5 Feb 2025 23:51:09 GMT, Alexey Semenyuk <asemenyuk at openjdk.org> wrote:

> Move junit tests to `share` subfolder.
> 
> Adjust `TEST.properties` to grant full access to classes in all `jdk.jpackage` module packages. Otherwise, jtreg picks access config from the parent [`TEST.properties`](https://github.com/openjdk/jdk/blob/aad6664bb6d2b311b3e0cb056afaa9b6534bdbbb/test/jdk/tools/jpackage/TEST.properties), which allows full access to `jdk.jpackage.internal` package only.

Looks good.

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Marked as reviewed by almatvee (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/23479#pullrequestreview-2597487823