feat: Add layerID to package struct in report

Hello,

When I want to check the licenses of a given images, it is important to me to understand in which layer the package exists.
This information is already provided by syft, is it possible to display it in grant as well?

Thanks for your time!

Start by locating the package struct used in grant's report and trace how Syft package metadata is read. Carry the layerID into the report output, then verify that a package's layer is displayed and update the relevant coverage if the project has tests for report generation.

Written by the indexing model from the issue text.