Fix silent failure of kustomize version with invalid output format

[saitejabandaru-in]

Fixes #6032

When using kustomize version --output=yml or any invalid output format, the command used to silently succeed without any output. This PR adds validation to return an error if the output format is not yaml or json, similar to how kubectl version behaves.

[kubernetes-prow]

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[kubernetes-prow]

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This pull-request has been approved by: saitejabandaru-in
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[kubernetes-prow]

Hi @saitejabandaru-in. Thanks for your PR.

I'm waiting for a kubernetes-sigs member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work.

Regular contributors should join the org to skip this step.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

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Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository.