[Runtime convergence] New tck/API to retrieve dataset full content

To enable Join processor with dataset, add an API to retreive dataset content.

• Add a service interface to component-api that allow to retrieve data from dataset configuration of another connector.

• Implementation of this new Service use same strategy as method ComponentManager.findMapper to find a simple Emitter linked to the dataset (without extra configuration); and build an iterator based on this emitter (producer).