Create Initial integration MVP with Work Item Handlers

The goal of this JIRA (epic) is to provide a resource content API, but we also believe that the best way to write this type of API is to validate with a real use case scenario.

As the original implementation of WorkItemDefinitionClientService was just an empty one, we decided to go ahead and implement a simple and naive implementation of the parser. That implementation was not targeted to become a production-ready implementation neither full support for most common use cases, it was just implemented to validate the Resource Content API and in the future, and with the option of becoming a starting point implementation for stunner team.

That is the main reasoning behind why we cut some corners in the parser implementation and also don't provide coverage for this and full use case implementation for it.