Add tag for package_uid in PACKAGES data for Docker images

[mjherzog]

We need to add the Docker-style tag data to each package_uid record in PACKAGES. We need this data to organize Package reporting by layer such as identifying the Packages from the Base image layer. We can only do this now by cross-referencing to the tags for Resources for_packages in the RESOURCES data.

[tdruez]

@mjherzog layer tag added on the Package model and set during the Docker pipeline. It's also available as a new column in the PACKAGES tab of the XLSX exports.

[mjherzog]

Excellent. Thank you.