Depends on patched apt-pkg-native-rs. Changelog-URL detection is
inspired by PVE perl code for now, though marked with fixme to use 'apt
changelog' later on, if/when our repos have APT-compatible changelogs
set up.
list_installed_apt_packages iterates all packages and creates an
APTUpdateInfo with detailed information for every package matched by the
given filter Fn.
Sadly, libapt-pkg has some questionable design choices regarding their
use of 'iterators', which means quite a bit of nesting...
Signed-off-by: Stefan Reiter <s.reiter@proxmox.com>