[Sample] Add back a policy with KMS verification

[chipzoller]

Problem Statement

GCPKMS verification doesn't seem to work in Kyverno 1.7.2, and owing to the breaking changes in Cosign which forced us to adopt 1.9.0 internally, earlier versions of 1.7.x do not work at all. As a result, I had to remove the image verification sample which uses GCPKMS. Once https://github.com/kyverno/kyverno/issues/4330 is resolved, we can add such a sample back.

Solution Description

Add a sample policy that illustrates how to verify an image using a GCP KMS key.

Example "Good" Resource

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Example "Bad" Resource

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Other Comments

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Slack discussion

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Troubleshooting

• [X] I have read and followed the documentation AND the troubleshooting guide.
• [X] I have verified the policy does not exist in the samples library.