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.
------------- Commit messages: - Move shared junit tests from "junit" to "junit/share" folder in preparation for adding platform-specific junit tests Changes: https://git.openjdk.org/jdk/pull/23479/files Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=23479&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8349504 Stats: 7 lines in 10 files changed: 5 ins; 0 del; 2 mod Patch: https://git.openjdk.org/jdk/pull/23479.diff Fetch: git fetch https://git.openjdk.org/jdk.git pull/23479/head:pull/23479 PR: https://git.openjdk.org/jdk/pull/23479
