Expose release version in metrics endpoint

Update the metrics endpoint in the operator to include:
Operator version & Product version e.g.

3scale_version_info{version=”1.2.3”,operator_version=”3.4.5”}

https://docs.google.com/document/d/1tkhKxwszM7NCRwJaa1zMyJaYBubq3FjVlUvVcIcykW4/edit?ts=5dd6b57e#