Consider using ImageTagMirrorSets alongside ImageDigestMirrorSet

[sva-andreasb]

Feature and motivation

Please consider using ImageTagMirrorSets along the already used ImageDigestMirrorSets. It happened a few times in the last releases that IBM somewhere used a Tag for referencing an image. In a disconnected environment without ImageTagMirrorSets this leads to errors when using these images, so we either have to skip a version or to manually update the used image to a digest. This is not always simple or possible.

Usage example

Using Maximo in a disconnected environment, when IBM accidentally references an image with a tag instead of a digest