Describe the bug

Currently, in order to get digest ref to the pushed image, one has to use --image-refs option introduced in #1217

There's already a TODO in the relevant code for this;

To Reproduce

Expected behavior

crane push should output to stdout like

Additional context

Add any other context about the problem here.

• Output of crane version
• Registry used (e.g., GCR, ECR, Quay)