Support digest for kube-rbac-proxy

[trevorndodds]

In mirror install, all images are rewritten with ImageContentSourcePolicy which by default uses digest.
With ecr operator it has no issue rewriting "quay.io/mobb/ecr-secret-operator:v0.4.1" but fails with gcr.io/kubebuilder/kube-rbac-proxy as its tag based.

Please can you add digest support for it. currently I have to patch the operator and delete the deployment to work around it.

Thanks