RFR: 8214158: Implement HostServices.showDocument on macOS without calling AWT [v4]

[Michael Paus]

> Fixes the issue by using the "open" command as discussed before.
> See: https://bugs.openjdk.java.net/browse/JDK-8214158

Michael Paus has updated the pull request incrementally with one additional commit since the last revision:

  Move test to subfolder HostServices

-------------

Changes:
  - all: https://git.openjdk.java.net/jfx/pull/634/files
  - new: https://git.openjdk.java.net/jfx/pull/634/files/f2f70d60..4e510dec

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jfx&pr=634&range=03
 - incr: https://webrevs.openjdk.java.net/?repo=jfx&pr=634&range=02-03

  Stats: 0 lines in 4 files changed: 0 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jfx/pull/634.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx pull/634/head:pull/634

PR: https://git.openjdk.java.net/jfx/pull/634