Generate a manifest of packages used at build time
At ISO build time, generate a list of used packages and version, including packages used at build time but not shipped in the ISO.
Output: a machine-readable file that sums up all the information we’ll later need to create a tagged, partial snapshot of the APT repositories we use, that contains only packages that were used at ISO build time.
Feature Branch: feature/10748-gen-packages-manifest
Parent Task: #9489 (closed)