RFR: 8372290: jpackage test lib improvements [v2]

[Alexey Semenyuk]

> Collect updates to jpackage test lib from different work-in-progress fixes:
> 
>  - ConfigFilesStasher: fix "ServiceTest.testAddLFromAppImage" test failure on Linux
>  - Move PropertyFile class to the package level and make it not throw IOException
>  - Update test/jdk/tools/jpackage/clean_stashed_files.sh and test/jdk/tools/jpackage/clean_test_output.sh scripts
>  - CannedFormattedString: make it implement CannedArgument; add `addPrefix()`, and `mapArgs()`
>  - JPackageCommand: add `makeError()` and `makeAdvice()`
> 
> Additionally:
>  - Add a test case to the AppImagePackageTest test to test that jpackage placed launcher .so in the correct location when using the predefined app image and installing the "/usr" tree on Linux
>  - Reduce code duplication in LauncherAsServiceVerifier.java

Alexey Semenyuk has updated the pull request incrementally with one additional commit since the last revision:

  AdditionalLauncher: use Slot class

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/28439/files
  - new: https://git.openjdk.org/jdk/pull/28439/files/33cee1b0..b974de7c

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=28439&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=28439&range=00-01

  Stats: 4 lines in 1 file changed: 1 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/28439.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/28439/head:pull/28439

PR: https://git.openjdk.org/jdk/pull/28439