RFR: 8377897: jpackage: make jdk.jpackage.internal.MockUtils available from other packages

[Alexey Semenyuk]

- Move jdk.jpackage.internal.MockUtils to jdk.jpackage.test.stdmock.JPackageMockUtils
 - Make ObjectFactory, ExecutorFactory, RetryExecutorFactory, and Executor accessible for creating jpackage mocks in tests outside the jdk.jpackage.internal package

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Commit messages:
 - Make ObjectFactory, ExecutorFactory, RetryExecutorFactory, and Executor accessible for creating jpackage mocks in tests outside the jdk.jpackage.internal package. Relocate MockUtils from jdk.jpackage.internal to jdk.jpackage.test.stdmock.JPackageMockUtils. The jdk.jpackage.test.stdmock package will contain jpackage-specific mock implementations.
 - DefaultBundlingEnvironment: move CachingSupplier to the utils package and fix a race condition (with AtomicReference it allowed calling the supplier twice)

Changes: https://git.openjdk.org/jdk/pull/29536/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=29536&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8377897
  Stats: 786 lines in 20 files changed: 467 ins; 266 del; 53 mod
  Patch: https://git.openjdk.org/jdk/pull/29536.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/29536/head:pull/29536

PR: https://git.openjdk.org/jdk/pull/29536