Merge beans.xml files for Embedded Weld Containers

Weld Embedded use a FlatDeployment structure and does not support nested Bean Archive Deployments like a Application Server does. To activate interceptors etc they have to be activated via beans.xml in all Bean Archives.

Since the Weld Embedded Container discovers and hands of all beans.xml files found in the Deployment and use a flat deployment structure, Weld will rightfully complain about duplicate entries if multiple nested BeanArchives within e.g. a WebArchive use the same Interceptors. To avoid this, and to avoid moving to a full Nested Bean Archive deployment structure we should merge the found beans.xml files into one definition and remote duplicate entries.