jlink native launcher support

jlink --launcher <name>=<module>[/<mainclass>] creates a launcher for the specified module/main class.

JDK 9 creates a script to run java -m <module>[/<mainclass>]. An enhancement is to create a native launcher to replace the script.

One idea is to have a prebuilt a tool launcher executable that reads a @argfile for the application. For example, jlink --launcher foo=org.foo/org.foo.Main

This will create a launcher $java.home/bin/foo and $java.home/bin/.foo_argfile
where .foo_argfile contains the VM options and -m org.foo/org.foo.Main.

Another alternative Jon suggests is to have the tool launcher to read from a static char array that will be patched by jlink to include the VM options plus the module/mainclass information.

The challenge would be for cross-platform linking and also ensure the prebuilt tool launcher executable supports the version of the target platform (likely that this executable may need to be copied from java.base.jmod)