[jdk17u-dev] RFR: 8344326: Move jpackage tests from "jdk.jpackage.tests" package to the default package

[Goetz Lindenmaier]

I backport this to simplify later test backports that touch the files in the new locations.

This is not based on the backport to 21.  That backport includes Comm.java.  When I did that, it had not planned to backport follow-up "8343876:` Enhancements to jpackage test lib" that brings Comm.java.  But as I did that in the meantime I think it is better to add that part there.  The backport from 21 would not have been clean, anyways,
nor backporting 8343876 from 21 on top.

Omitted PredefinedAppImageErrorTest.java‎. Was added by "8286850: [macos] Add support for signing user provided app image" in 19.

test/jdk/tools/jpackage/windows/WinL10nTest.java
Code modified was added by "8291978: jpackage: allow to override primary l10n files on Windows" in 20.  Omitted.

BasicTest.java requires TKit.assertDirectoryContent(). This was added by 8325089: jpackage utility creates an "infinite", undeleteable directory tree.
Too big to backport as prereq, so I add that to TKit as I already did in the backport to 21.

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Commit messages:
 - TKit from 8325089 for BasicTest.java
 - backport 2c509a158fad63e69a8072fa4a7588eaacf37dc0

Changes: https://git.openjdk.org/jdk17u-dev/pull/4105/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=4105&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8344326
  Stats: 159 lines in 21 files changed: 85 ins; 39 del; 35 mod
  Patch: https://git.openjdk.org/jdk17u-dev/pull/4105.diff
  Fetch: git fetch https://git.openjdk.org/jdk17u-dev.git pull/4105/head:pull/4105

PR: https://git.openjdk.org/jdk17u-dev/pull/4105