WIP: JDK-8214158 : (JavaFX) Default to open for document opening on macOS

[Tristan971]

WIP/draft for now, have to ensure a few things first and also a kind of open question down below, but should be the general idea.

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Fixes #294. Unsure if the try-catch is needed. I guess it's a light price to pay to ensure (almost) total backwards compatibility in the matter although it is definitely not really needed as macOS environments are much less different from one to the other than Linux ones.

Let me know your thoughts on whether to straight-up replace the previous command or keep this proposed wrapping.

[kevinrushforth]

I won't be able to get to this right away. If we go this route, a fallback is probably not necessary.

One thing of note is that the AWT code, which we are currently calling, uses a native method to call LSOpenURLsWithRole rather than "exec"-ing a new process from Java. I'm not sure why (maybe the open command wasn't as robust when it was implemented? Or maybe there is some benefit to using LSOpenURLsWithRole?), but we will need to make sure that there isn't a regression in behavior as a result.

[Tristan971]

Yep I have a few concerns about subprocess hierarchy for example like shutting down jvm maybe shutting down browser, I want to do some testing about it beforehand.

[kevinrushforth]

I removed myself as a reviewer until this is ready for review (currently it is WIP).

[kevinrushforth]

As announced in this message, the official jfx repository is moving from hg.openjdk.java.net/openjfx/jfx-dev/rt to github.com/openjdk/jfx.

This sandbox repository is being retired on 1-Oct-2019. You will need to migrate your WIP pull request to the openjdk/jfx repo if you want to continue working on it. Here are instructions for migrating your pull request. The updated CONTRIBUTING.md doc has additional information on how to proceed.

Once you have done this, it would be helpful to add a comment with a pointer to the new PR.

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The new openjdk/jfx repo will be open for pull requests on Wednesday, 2-Oct-2019. I will send email to the openjfx-dev mailing list announcing this.