[TESTBUG] Create additional two phase jpackage tests

Several things can be different if you
1.) create a package in one step vs. if you
2.) create an app-image then use that app image to create a package.
In particular we should test creating an app image with several additional launchers, then creating packages with either --linux-shortcut or --win-shortcut specified.
The point would be to verify that shortcuts are created for all launchers