Minor improvements and updates
- Add metadata analysis tools used by SecureDrop (Closes: #17178)
- Refresh the signing key before checking for available upgrades
(Closes: #15279)
- Port the Upgrader and perl5lib to a set of dependencies that are
faster and have a lower memory footprint (Closes: #17152)
- Ensure IUKs don't include files of our website if their content
has not changed (refs: #15290)
- Zero heap memory at allocation time and at free time (Closes: #17236)