Support Prometheus scraping

For testing that an application is working correctly also from a management point of view, I think it would be nice if Yaks could support reading Prometheus data that the application produces.
It would be useful to test that the application publishes the expected metrics to the monitoring solution.

Some scenarios:
- (Deep Inspection) Yaks can deploy an application and then test (via Prometheus) that it does not produce errors/warnings on startup
- (Metrics) Yaks can deploy an application, trigger a certain number of events of different types, then verify that produced metrics agree with the data that has been processed
- (Anomalies) Yaks can deploy an application with a wrong network configuration (cannot reach external system), then it verifies that the appropriate event is triggered in Prometheus to signal the anomaly

I think there are other use cases that are valid.

Looking around for Java Prometheus scrapers, I've only found this one: https://github.com/jmazzitelli/prometheus-scraper. I don't know if there are others that are up to date (or officially supported).