Bug 1135473 - Implicit Variables for CLI are not available if the script is run as notification on an alert

Script engine was initialized with an empty list of core domain packages.

In the "real" CLI we can find it by scanning the lib directory. Here, we need to scan the core domain JAR by inspecting the classloader.

Re-used org.jboss.jandex module from the EAP6.3 base instead of importing a new lib or writing our own code.