[FEATURE]: Allow specifying an alternative container registry

[mruoss]

Hey there

It would be nice if the operator allowed for specifying a separate container registry. Use case: I'd like to rely on the channel and version logic but prefer the images to be pulled from our internal "proxy" registry.

Edit: I will try to control this using the imageName field of the upgrade-path configmap. Keeping you posted.  <= doesn't work as that field is not kustomizeable by itself.

Thanks,
Michael