Merge pull request #20672 from brendandburns/dump

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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docs/yaml/kubectl/kubectl_cluster-info.yaml

@@ -1,7 +1,8 @@
 name: cluster-info
 synopsis: Display cluster info
-description: |
+description: |-
   Display addresses of the master and services with label kubernetes.io/cluster-service=true
+  To further debug and diagnose cluster problems, use 'kubectl cluster-info dump'.
 options:
 - name: include-extended-apis
   default_value: "true"
@@ -70,3 +71,4 @@ inherited_options:
     comma-separated list of pattern=N settings for file-filtered logging
 see_also:
 - kubectl
+- dump