feat: start, stop, restart, enable and disable services, and list them in one round trip

napalm-device-types' SystemdServicesMixin (2.2.0) now provides get_services()
and manage_service(); this driver supplies only the transport (#7):

- _run_service_command(): unprivileged reads and root logins run as they
  are -- the user is asked once per session with "id -u", so a root login on a
  box without sudo is not prefixed with one. With a sudo password the command
  goes through _sudo(); without one through "sudo -n", which fails at once
  instead of hanging the session on a password prompt until the read timeout.
- get_services(): one round trip instead of an is-enabled and a show per unit
  (6.0 s -> 0.8 s on a 184-unit Ubuntu host). A host without systemd still
  falls back to "service --status-all".
- manage_service(): when sudo wants a password netOrk does not have, the
  failure says how to fix it -- the same hint the apt and SNMP actions give,
  now one constant (_SUDO_PASSWORD_HINT) instead of two copies.

OpenMediaVault and QNAP inherit this driver. OMV gets service control with
it; QNAP opts out (napalm-qnap-qts), since QTS has no systemd.

README: the sudo option is sudo_password, not secret; manage_service and the
systemctl permissions are listed.

Closes #7

pyproject.toml

@@ -37,7 +37,7 @@ classifiers = [
 ]
 dependencies = [
     "napalm>=4.0",
-    "napalm-device-types>=2.1.0",
+    "napalm-device-types>=2.2.0",
     "netmiko>=4.0.0",
     "paramiko>=5.0.0",  # CVE-2026-44405
 ]