feat: get_service_packages, which packages a systemd service is (NetOrk/netork#1236)

Mixes in napalm-device-types' ServicePackagesMixin. The transport runs the
shared read-only command on an exec channel under sh, without sudo: it is
about 1 kB, past what the PTY takes reliably, and written for sh whatever
the login shell. Requires napalm-device-types 4.20.0; version 0.12.0.

napalm_linux/linux.py

@@ -47,6 +47,7 @@ from napalm_device_types import (
     OSDriver,
     PackageProxyMixin,
     ServiceClustersMixin,
+    ServicePackagesMixin,
     SnmpAgentMixin,
     SystemIdentityMixin,
     SystemdServicesMixin,
@@ -294,6 +295,7 @@ class LinuxDriver(
     EnsurePackageMixin,
     PackageProxyMixin,
     KernelFactsMixin,
+    ServicePackagesMixin,
     ListeningSocketsMixin,
     VirtualIpsMixin,
     ServiceClustersMixin,
@@ -1164,6 +1166,15 @@ class LinuxDriver(
         """The transport for ``KernelFactsMixin.get_kernel_facts``: read-only, no sudo."""
         return self._send(command, read_timeout=60)
 
+    def _run_service_packages_command(self, command: str) -> str:
+        """The transport for ``ServicePackagesMixin.get_service_packages``.
+
+        An exec channel rather than the PTY -- the command is about 1 kB -- under
+        ``sh``, which it is written for, whatever the login shell. Read-only, so
+        never through sudo.
+        """
+        return self.run_command(f"sh -c {_shlex_quote(command)}", timeout=120).stdout
+
     # ------------------------------------------------------------------
     # ListeningSocketsMixin – the transport for get_listening_sockets
     # ------------------------------------------------------------------