Mage AI - publish Artifact level and User Defined Rules KPIs in Governance API

The goal is to publish the artifact level KPIs (dataset key) and User Defined Rules in Governance API.

This issue will be blocked by Governance API changes: eclipse-research-labs/datamite-project/data-governance/data-governance-backend#27 (closed)

Take into account the Governance DCAT refactor as well.

/cc @bnavarroiti