As a Quay user I want to see untagged artifacts in the UI.

An untagged artifact is for example an image that has been cached via pull-by-digest, or potentially an image signature (see below).

This is specially problematic for images cached via pull-thru, since a client pull-by-digest will cache the image, but the image will never show up in the UI due to the lack of a tag.

Another use-case for this is the upcoming OCI references[1], which will allow OCI artifacts to reference other artifacts in a registry (i.e a signature referencing a manifest).

[1] https://github.com/opencontainers/tob/blob/main/proposals/wg-reference-types.md#purpose