Make runnable on air-gapped Openshift environments

[muellerfabi]

We want to use this operator in combination with DevSpaces on an airgapped Openshift cluster.

• we use oc-mirror to mirror the operator to an internal registry [1]
• and ImageContentSourcePolicy (ICSP) in order to point "rewrite" the image to internal registry.

Now this does not work, because the images in CSV are set to use tags and ICSP only works with digest

• quay.io/eclipse/kubernetes-image-puller-operator:1.1.0
• quay.io/brancz/kube-rbac-proxy:v0.11.0.

Proposal:
Deliver the CSV to redhat community operator index containing digests rather than tags.

[1] https://docs.openshift.com/container-platform/4.12/updating/updating-restricted-network-cluster/mirroring-image-repository.html#update-mirror-repository-adm-release-mirror_mirroring-ocp-image-repository