RFR: 8293462: [macos] app image signature invalid when creating DMG or PKG from post processed signed image

[Alexander Matveev]

Problem is that [JDK-8286850](https://bugs.openjdk.org/browse/JDK-8286850) never set correct value in .jpackage.xml to mark image as signed. [JDK-8289030](https://bugs.openjdk.org/browse/JDK-8289030) reads this value to check if we can add per-user and system wide configuration to packaged app. Fixed by setting correct value in .jpackage.xml when we signing predefine application image.

Added tests to cover this case and added check for values inside .jpackage.xml to validate signed and Mac App Store values.

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Commit messages:
 - 8293462: [macos] app image signature invalid when creating DMG or PKG from post processed signed image

Changes: https://git.openjdk.org/jdk/pull/10316/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=10316&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8293462
  Stats: 367 lines in 12 files changed: 303 ins; 15 del; 49 mod
  Patch: https://git.openjdk.org/jdk/pull/10316.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/10316/head:pull/10316

PR: https://git.openjdk.org/jdk/pull/10316