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Support completions for --clusterrole of kubectl create clusterrolebinding

**What this PR does / why we need it**:
This PR supports completion for --clusterrole of kubectl create clusterrolebinding.
```
$ kubectl create clusterrolebinding hoge --clusterrole <tab>
admin                                         system:controller:daemon-set-controller       system:controller:node-controller             system:controller:service-controller          system:kube-scheduler
cluster-admin                                 system:controller:deployment-controller       system:controller:persistent-volume-binder    system:controller:statefulset-controller      system:node
edit                                          system:controller:disruption-controller       system:controller:pod-garbage-collector       system:controller:ttl-controller              system:node-bootstrapper
system:auth-delegator                         system:controller:endpoint-controller         system:controller:replicaset-controller       system:discovery                              system:node-problem-detector
system:basic-user                             system:controller:generic-garbage-collector   system:controller:replication-controller      system:heapster                               system:node-proxier
system:controller:attachdetach-controller     system:controller:horizontal-pod-autoscaler   system:controller:resourcequota-controller    system:kube-aggregator                        system:persistent-volume-provisioner
system:controller:certificate-controller      system:controller:job-controller              system:controller:route-controller            system:kube-controller-manager                view
system:controller:cronjob-controller          system:controller:namespace-controller        system:controller:service-account-controller  system:kube-dns
```

**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*: fixes #

**Special notes for your reviewer**:

I feel that it is better to except system clusterroles from completion candidates. What do you think about it?

**Release note**:

```release-note
Support completion for --clusterrole of kubectl create clusterrolebinding
```