RFR: 8214158: Implement HostServices.showDocument on macOS without calling AWT [v2]

[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:

  Add test

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Changes:
  - all: https://git.openjdk.java.net/jfx/pull/634/files
  - new: https://git.openjdk.java.net/jfx/pull/634/files/85654e56..ad9f268f

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jfx&pr=634&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jfx&pr=634&range=00-01

  Stats: 109 lines in 4 files changed: 109 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