Improve build of EIK repository and update artifact/content jar

The org.apache.karaf.eik.repository provides artifacts.jar and content.jar.
These jar files are just wrapper for XML files. However, the wrapped XML files should be updated to reference the correct artifacts.

Instead of just putting the jar file into the module, it would be great to set the XML as src and to generate the jar files at build time.

Moreover, the current jar files are not up to date currently.