Automatic merge from submit-queue

Add a 'kubectl clusterinfo dump' option

Ref: #3500 

@bgrant0607 @smarterclayton @jszczepkowski 

Usage:
```
  # Dump current cluster state to stdout
  kubectl clusterinfo dump
  
  # Dump current cluster state to /tmp
  kubectl clusterinfo dump --output-directory=/tmp
  
  # Dump all namespaces to stdout
  kubectl clusterinfo dump --all-namespaces
  
  # Dump a set of namespaces to /tmp
  kubectl clusterinfo dump --namespaces default,kube-system --output-directory=/tmp
```

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