RFR: 8370136: Support async execution of jpackage tests

[Alexey Semenyuk]

$subj

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Commit messages:
 - Support async test execution in jpackage test lib

Changes: https://git.openjdk.org/jdk/pull/27877/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=27877&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8370136
  Stats: 362 lines in 7 files changed: 215 ins; 63 del; 84 mod
  Patch: https://git.openjdk.org/jdk/pull/27877.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27877/head:pull/27877

PR: https://git.openjdk.org/jdk/pull/27877