improvise metrics collection

[joelrebel]

• Enlist metrics to be collected
• Enable metrics collection for every component, its currently disabled in various components,
  for e.g https://github.com/bmc-toolbox/bmcbutler/blob/master/pkg/inventory/enc.go#L365
• Validate metrics are being collected - using tests.

[paskal]

I think validating metrics collection is not worth it: it's not easy to mock and it's easier to detect visually on Grafana dashboard or wherever you send them instead of putting unit tests on them.