feat: get_system_identity for matching a host to its BMC (0.7.0)

Mixes in napalm-device-types 4.9's SystemIdentityMixin: the host's
SMBIOS system UUID, product serial and board serial, read as root on an
exec channel, vendor placeholders empty. netOrk links a server's BMC to
the host on these.

napalm_linux/linux.py

@@ -43,6 +43,7 @@ from napalm_device_types import (
     ListeningSocketsMixin,
     OpenSshServerMixin,
     OSDriver,
+    SystemIdentityMixin,
     SystemdServicesMixin,
     SystemdUnavailable,
     VirtualIpsMixin,
@@ -245,6 +246,7 @@ class LinuxDriver(
     KernelFactsMixin,
     ListeningSocketsMixin,
     VirtualIpsMixin,
+    SystemIdentityMixin,
     OpenSshServerMixin,
     SystemdServicesMixin,
     HostStatusMixin,
@@ -1131,6 +1133,11 @@ class LinuxDriver(
         """
         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."""
+        return self.run_command(command, privileged=privileged, timeout=30).stdout
+
     # ------------------------------------------------------------------
     # OSDriver – package management
     # ------------------------------------------------------------------