[Data Discovery Pipelines] - send general score to GovernanceAPI

Quality Evaluator is now sending the general score at artifact level.

QE return model example

The attribute is located at root level. In the below example: "rules_overall_score": 60.55884286653517

If there are no active rules, the QE will return a null value in the rules_overall_score property.

/cc @bnavarroiti, @imurua