[discussion] allow oci_pull with tag + digest

[malt3]

This is a follow-up from renovatebot/renovate#21216

Dependency management tools like renovate can use the tag of a container image for more informed upgrades
Users can even define custom policies and versioning schemes to have fine control over what upgrades should be suggested.

I could see us allowing both tag and digest to be set and making digest override tag.
@thesayyn

[Cartman75]

I would like this. As stated. When renovate send me an update, I understand the difference between just hash updates because the container changed with the same version and when the actual version of the image is changing, not just the hash.

[thesayyn]

Discussion is ongoing at #391