Support for application-specific metrics tracking

[devdattakulkarni]

Currently, KubePlus tracks the following metrics by default: CPU, memory, ingress network, egress network, and storage. We should support the ability to track application-specific metrics through ResourceMonitor CRD. The assumption here will be that the application exposes such metrics at some endpoint that KubePlus is able to scrape and surface out for ingesting into Prometheus.