Summary of changes:
  * Added Eclipse feature definition
  * Added Eclipse repository definition
  * Added Maven-based Standalone library build
    * Supports deploying to GitLab package repository as Maven artifact
    * Tests are executed during the build in a standard Java runtime
  * Added Maven-based Eclipse plugin build
    * Supports uploading to a remote server as an Eclipse repository
    * Tests are executed during the build in the Eclipse environment
  * Added Eclipse run configurations for
    * Building, installation, and deployment of both build variants
    * Updating the versions of both build variants
  * Fixed loading of extensions in the Eclipse environment