Add request handlers to v2 implementation

**What would you like to be added**:
Follow up from #131, add AWS request handlers to do the following:

* Add metrics
* Add rate limiting

@M00nF1sh , do you think it's worth re-implementing what's done in in https://github.com/aws/aws-app-mesh-controller-for-k8s/tree/master/pkg/aws for the above?

FWIW, I used the same metric formats in https://github.com/kubernetes-sigs/cluster-api-provider-aws/blob/master/pkg/cloud/metrics/metrics.go, so would be worth standardising.

**Why is this needed**:

/kind feature