Draft: Health of the infrastructure to be captured in the Operations Admin portal

The SOG needs to know when a site is down. This will help debug service level issues, identify how the SRCNet needs to respond (eg, are all services down or is the infrastructure down?), and understand load distribution across SRCNodes. 

Eventually, this might help gain insight to how user payloads perform on different sites (if the metrics reported are rich and enable this)

Node exporter is an industry standard cloud native tool that gathers kubernetes nodes metrics to be served into Prometheus/Grafana. Prometheus configured to point to node-exporter services at 2 different sites. Grafana dashboards to view node health per site.