To enhance operatability for the service using norman framework,
It's better to expose internal state as detail as possible.
This is the just starting point but at least which handler is executed
often and which handler with which key's execution is often failed
metrics is very useful to spot the place operator have to dig in when
something happened.
So this commit added 2 metrics.
1: handler execution total count
2: handler execution failure total count
With the built in prom. metrics provider, the k8s machinery doesnt
deregister metrics when controllers are removed. So over time as
things like clusters are created or removed the metrics are not
cleaned up. The metrics types for the cache and queue are also
very large. They can take ~1GB of RAM in a 100 cluster setup.
Also, Rancher is not exposing these stats so they are unobservable.
