Move OPA Gatekeeper namespace exceptions to resource exceptions

With !785 (merged), you can now create exceptions on namespace + resource_name. With all of the exceptions in /chart/templates/gatekeeper/values.yaml, convert them to use namespace + resource_name instead.

In addition, update the development and test values:

• chart/k3d-dev-values.yaml
• tests/ci/k3d/values.yaml

Lastly, update documentation that references the exceptions for k3d.