Add support for pipeline runtime specific components

[lresende]

Enable the notion of a registry that can parse and expose the necessary information required to expose runtime specific components on the Elyra pipeline editor.

Examples of KFP Components:

• https://github.com/kubeflow/pipelines/tree/master/components Example of Airflow Components:
• https://github.com/apache/airflow/tree/1.10.15/airflow/operators
• https://github.com/apache/airflow/tree/1.10.15/airflow/contrib/operators

Things to consider:

• Abstraction of classes to enable the concept of "federated registry" that reads from different sources/locations/types
• Caching on multiple layers: Frontend, Service, Filesystem contents

[Jeffwan]

I think it would be great to have some abstraction to import verified components to a box (could be a elyra concept) on cavas.

[lresende]

I think it would be great to have some abstraction to import verified components to a box (could be a elyra concept) on cavas.

@Jeffwan we are finally working on the implementation of the registry functionality to register and serve additional components to the pipeline editor. Do you want to create a new issue for "importing verified components" and we would add it to the umbrella issue we have for Pipeline Editor 2.0. Please describe your requirements on the issue, I was thinking initially maybe a CLI and subsequently maybe some sort of admin UI similar to what we have for runtimes, etc?