feat: read the service clusters a host belongs to (0.10.0)

LinuxDriver mixes in napalm-device-types' ServiceClustersMixin (4.17.0):
get_service_clusters() reads Patroni's members and roles, adguardhome-sync's
origin and replicas and a BunkerWeb worker's manager from the host's own
configuration -- the evidence that two hosts run one service, not merely
answer at one address (NetOrk/netork#1125). _run_service_clusters_command
carries the shared command on an exec channel, root first, like the virtual
IPs' one.

napalm_linux/linux.py

@@ -46,6 +46,7 @@ from napalm_device_types import (
     OpenSshServerMixin,
     OSDriver,
     PackageProxyMixin,
+    ServiceClustersMixin,
     SnmpAgentMixin,
     SystemIdentityMixin,
     SystemdServicesMixin,
@@ -294,6 +295,7 @@ class LinuxDriver(
     KernelFactsMixin,
     ListeningSocketsMixin,
     VirtualIpsMixin,
+    ServiceClustersMixin,
     SystemIdentityMixin,
     OpenSshServerMixin,
     SystemdServicesMixin,
@@ -1179,6 +1181,13 @@ class LinuxDriver(
         """
         return self.run_command(command, privileged=privileged, timeout=60).stdout
 
+    def _run_service_clusters_command(self, command: str, *, privileged: bool) -> str:
+        """The transport for ``ServiceClustersMixin.get_service_clusters``: an exec
+        channel, like the virtual IPs' command, which it resembles in size.
+        Read-only either way; root only because Patroni's configuration is the
+        postgres user's alone."""
+        return self.run_command(command, privileged=privileged, timeout=60).stdout
+
     def _run_system_identity_command(self, command: str, *, privileged: bool) -> str:
         """The transport for ``SystemIdentityMixin.get_system_identity``: an exec channel,
         as root, since ``product_uuid`` and ``product_serial`` are root's."""