Introduce Goldpinger as optional unit for connectivity monitoring inside cluster

Add Goldpinger as an optional unit inside Sylva to be able to monitor and visualize pod-to-pod network connectivity. Goldpinger runs as a DaemonSet and uses HTTP calls between pods to report on network health, helping to identify network outages and latency issues.

It also produces Prometheus metrics that can be scraped, visualised and alerted on.

Goldpinger can be installed with helm.

Goldpinger will enhance observability and support debugging of inter-node networking issues and not only, it also supports monitoring http/s or tcp reachability to destinations outside the cluster.

Goldpinger UI is accessible via a service (NodePort or Ingress) for dashboard viewing, but since it hasn't any built-in authentication available, it should only be exposed during troubleshooting sessions.

Example of Goldpinger UI when one node (out of three) is isolated: image

Note: different issue was created to implement monitoring for cluster connectivity.

Edited by Vlad Onutu