Mark KEP implementable and add test plan

[arjunrn]

The KEP has been implemented. Also updated the test plan.

[k8s-ci-robot]

Hi @arjunrn. Thanks for your PR.

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[arjunrn]

/assign @mwielgus

[gjtempleton]

We should update this I think given its changing status and we're adding the test plan.

[gjtempleton]

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: arjunrn, gjtempleton

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