RFR: 8263154: [macos] DMG builds have finder errors

[Alexander Matveev]

- Issue was reproducible when install-dir points to some invalid location.
 - Fixed by defaulting DMG drag and drop location to /Applications folder and --install-dir will be ignored with warning for DMG.
 - I do not see any way to support other valid, but uncommon locations for drag and drop. For example: /Users/USERNAME/Applications is not possible to support since user name is not known. /usr/bin requires root privileges and should contain symbolic links. Locations which does not exist also not possible to support, since DMG cannot create paths. So /Applications/MyCompany is not possible for DMG.

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Commit messages:
 - 8263154: [macos] DMG builds have finder errors

Changes: https://git.openjdk.java.net/jdk/pull/3505/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=3505&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8263154
  Stats: 18 lines in 6 files changed: 7 ins; 0 del; 11 mod
  Patch: https://git.openjdk.java.net/jdk/pull/3505.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/3505/head:pull/3505

PR: https://git.openjdk.java.net/jdk/pull/3505