on-save plumbing for model operator

[mwdchang]

Summary

This PR changes the "save as" semantic for model-operator, such that on top of

• creating a new model
• adding the model into the project

It will also update the model-operator to take in the newly create model, any downstream operators will be invalidated as if a new output has been chosen.

Note

Because model-operator ceeds all control to tera-model component, we don't have a graceful way of isolating the logic to the model-operator itself. What we end up is tera-model will detect whether it is on the workflow-route or not, and emit an event back to the invoker. We will then catch that event in model-operator and do the usual update-state, append-output to propagate new changes.

Testing

• Add a model onto workflow canvas
• Link the model to a model-config operator
• Drilldown into the model operator, save as a new model with a different name

Check new model is created and available within the project
Check the new model replaces the existing one in the model-operator
Check the new model is the output of model-operator and downstream operators are invalidated because there is a new instance

[YohannParis]

LGTM