RFR: 8378867: jpackage references non-existing "message.app-image-requires-identifier" l10n key

[Alexey Semenyuk]

Fix missing l10n key. Add a test to cover the fix.

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Commit messages:
 - MacApplicationBuilder: fix missing "message.app-image-requires-identifier" key

Changes: https://git.openjdk.org/jdk/pull/29905/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=29905&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8378867
  Stats: 40 lines in 4 files changed: 34 ins; 3 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/29905.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/29905/head:pull/29905

PR: https://git.openjdk.org/jdk/pull/29905