jpackage: support for environment variables in --java-options

[Michael Hall]

> 
> The incident mentioned earlier showed a resolution of having the user provide their own custom Info.plist. While plain old edit would probably be fine for this some sort of code to provide it without manual intervention might also be nice. I believe I have some old code lying around that might just provide a beginning for such a thing.

As another possible alternative for working with an Info.plist this was recently mentioned on I think it was a Cocoa mail list. 
https://medium.com/@marksiu/what-is-plistbuddy-76cb4f0c262d <https://medium.com/@marksiu/what-is-plistbuddy-76cb4f0c262d>