RFR: 8352480: Don't follow symlinks in additional content for app images [v2]

[Alexander Matveev]

> - Symbolic links will not be followed for `--app-content` on all platforms.
> - Added test to cover this case.
> - `MacHelper` updated to use "cp -R" instead of "cp -r" when unpacking DMG, since "cp -r" on macOS is not documented option and when used `cp` will follow symbolic links which breaks test. "cp -R" does not follow symbolic links.

Alexander Matveev has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains five additional commits since the last revision:

 - Merge remote-tracking branch 'upstream/master' into JDK-8352480
 - 8352480: [macos] Don't follow symlinks in additional content for app images [v4]
 - 8352480: [macos] Don't follow symlinks in additional content for app images [v3]
 - 8352480: [macos] Don't follow symlinks in additional content for app images [v2]
 - 8352480: [macos] Don't follow symlinks in additional content for app images

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Changes:
  - all: https://git.openjdk.org/jdk/pull/24974/files
  - new: https://git.openjdk.org/jdk/pull/24974/files/004304ed..519be97e

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=24974&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=24974&range=00-01

  Stats: 30202 lines in 804 files changed: 21331 ins; 5103 del; 3768 mod
  Patch: https://git.openjdk.org/jdk/pull/24974.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/24974/head:pull/24974

PR: https://git.openjdk.org/jdk/pull/24974