Extract discovery code out of project examples

Discovery code used by central (to install software) and project-examples (to discover proxy-wizards) lives in project examples. Because of that dependency, project examples also contain API that configures central content. That forces com.jboss.devstudio.core.central to depend on project examples, just to configure central contents.

This sucks big time and that common discovery code should be extracted to another component, consumed by both central and examples. The central configuration API should move back to central.