JPMS - Add Automatic-Module-Name entry in the manifest (or module-info.java)

To simplify for downstream Java module consumers, it would be nice if the pkts-xxx artifacts/jar were Java 9 modules, or at the very least have an entry `Automatic-Module-Name` in the manifest.

https://dzone.com/articles/automatic-module-name-calling-all-java-library-maintainers

E.g. pkts-core would have the module name "io.pkts.core".