Create partial APT snapshot from a build manifest and a set of time-based snapshots

This is mainly about the tails-prepare-tagged-apt-snapshot-import script (puppet-tails repo) and the glue + Puppet bits that will make it usable.

Blueprint: https://tails.boum.org/blueprint/freezable_APT_repository/

Parent Task: #9489 (closed)

Related issues

• Blocks #6310 (closed)

Original created by @intrigeri on 10749 (Redmine)