RFR: 8350102: Decouple jpackage test-lib Executor.Result and Executor classes

[Alexey Semenyuk]

8350102: Decouple jpackage test-lib Executor.Result and Executor classes

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Commit messages:
 - Bugfix Executor.createResult() and add Executor.getExecutable()
 - Decouple Executor.Result and Executor classes

Changes: https://git.openjdk.org/jdk/pull/23636/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=23636&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8350102
  Stats: 48 lines in 3 files changed: 15 ins; 7 del; 26 mod
  Patch: https://git.openjdk.org/jdk/pull/23636.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/23636/head:pull/23636

PR: https://git.openjdk.org/jdk/pull/23636