Add validation check for policies that use filtered kinds

[JimBugwadia]

Is your feature request related to a problem? Please describe.

Kyverno allows filtering certain API kinds to optimize webhook processing.

However, users may create policies that use these types and not realize a filter is skipping policy execution.

Describe the solution you'd like

Kyverno should validate policies that use filtered kinds and provide a warning, or block them from being created.

If in the future we dynamically manage webhook registrations on a more granular basis (see: #1981), perhaps the static filtering can be removed and then this check will no longer be necessary.

Describe alternatives you've considered

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Additional context

See discussion in the PR: kyverno/policies#81 (comment)

[chipzoller]

Is this issue still relevant since dynamic webhooks are implemented?

[realshuting]

No longer valid, closing.