feat: report a dpkg left halfway and when the host's own automatic updates last succeeded

An unattended upgrade cut off while it built an initrd left a kernel package
half-configured on an Ubuntu host. For three months apt refused every upgrade,
while apt.systemd.daily exited quietly and the timers reported success
(NetOrk/netork#738).

HOST_STATUS_COMMAND now also reads, without root:

- dpkg's state the way apt checks it: numbered files left in
  /var/lib/dpkg/updates, or a package half-installed, unpacked,
  half-configured, waiting for triggers or flagged for reinstallation.
  While dpkg, apt, aptitude or unattended-upgrade runs, packages are
  halfway on purpose, so the answer is then None.
- /var/lib/apt/periodic/upgrade-stamp, which apt.systemd.daily touches only
  after unattended-upgrade succeeded, and the interval of
  APT::Periodic::Unattended-Upgrade in apt's units. update-success-stamp is
  not read: every apt-get update touches it, whoever runs it.

HostStatusDict gains package_manager_interrupted, interrupted_packages,
auto_updates_last_success and auto_updates_interval, all NotRequired.

pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "setuptools.build_meta"
 
 [project]
 name = "napalm-device-types"
-version = "4.2.0"
+version = "4.3.0"
 description = "Abstract device-type base classes for NAPALM drivers"
 readme = "README.md"
 requires-python = ">=3.10"