[jdk19] RFR: 8289030: [macos] app image signature invalid when creating DMG or PKG

[Alexander Matveev]

Fixed 3 issues which made signature invalid:
- We should not remove .jpackage.xml from signed app image when creating DMG or PKG otherwise it invalidates signature.
- .package should be created when app image is generated, so this file can be signed.
- Copying predefine app image for DMG and PKG should not follow symbolic links, otherwise several files from runtime (COPYRIGHT and LICENSE) will be copied instead of symbolic links being created, since it invalidates signature as well.

Added additional test to validate signature when DMG or PKG is generated from predefined app image.

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Commit messages:
 - 8289030: [macos] app image signature invalid when creating DMG or PKG

Changes: https://git.openjdk.org/jdk19/pull/89/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk19&pr=89&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8289030
  Stats: 149 lines in 5 files changed: 134 ins; 6 del; 9 mod
  Patch: https://git.openjdk.org/jdk19/pull/89.diff
  Fetch: git fetch https://git.openjdk.org/jdk19 pull/89/head:pull/89

PR: https://git.openjdk.org/jdk19/pull/89