fix '--user' flag conflict in create rolebinding command

[Lion-Wei]

What this PR does / why we need it:

--user is kubectl global flag, but kubectl create rolebinding and other command also have this flag with other meaning, that will result in Kubectl doesn't respect --user parameter.

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes kubernetes/kubectl#188

Special notes for your reviewer:

Change --user flag in kubectl create clusterrolebinding and other command to --roleuser.

Release note:

NONE

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: Lion-Wei
We suggest the following additional approver: brendandburns

Assign the PR to them by writing /assign @brendandburns in a comment when ready.

Associated issue: #188

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• pkg/kubectl/OWNERS

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[Lion-Wei]

/cc @apelisse
@mpashka
/sig cli
/kind bug

[apelisse]

/ok-to-test

Discussion is happening on the issue:
/hold

[k8s-ci-robot]

@Lion-Wei: The following tests failed, say /retest to rerun them all:

Test name	Commit	Details	Rerun command
pull-kubernetes-verify	bbe7e0e	link	/test pull-kubernetes-verify
pull-kubernetes-unit	bbe7e0e	link	/test pull-kubernetes-unit

Full PR test history. Your PR dashboard. Please help us cut down on flakes by linking to an open issue when you hit one in your PR.

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[liggitt]

I don't think we'll change the command at this point, it would break too many uses
/close