feat: report a FreeBSD host as needing a reboot when its installed kernel is not the running one

HOST_STATUS_COMMAND also prints freebsd-version -k and -r where
freebsd-version exists. When the two differ, a kernel update was installed
and is not running yet, so the host needs a reboot. When they match, it does
not.

napalm_device_types/host_status.py

@@ -16,6 +16,8 @@ carries the command across.
 - A kernel newer than the running one is installed, of the same flavour. A
   Raspberry Pi carries ``rpi-v8`` and ``rpi-2712`` builds side by side, and only
   the running one's counts.
+- On FreeBSD, ``freebsd-version -k`` (the installed kernel) differs from
+  ``freebsd-version -r`` (the running one): a patch replaced the kernel.
 
 It is ``None`` when none of these could be read, for example in a container
 without a ``/lib/modules`` of its own.
@@ -50,6 +52,9 @@ HOST_STATUS_COMMAND = (
     "if command -v needs-restarting >/dev/null 2>&1; then echo '[needs-restarting]'; "
     "needs-restarting -r >/dev/null 2>&1; echo $?; fi; "
     "echo '[kernel]'; uname -r; echo '[modules]'; ls -1 /lib/modules 2>/dev/null; "
+    "if command -v freebsd-version >/dev/null 2>&1; then "
+    "echo '[freebsd-kernel]'; freebsd-version -k; "
+    "echo '[freebsd-running]'; freebsd-version -r; fi; "
     "if command -v apt-config >/dev/null 2>&1; then echo '[apt-config]'; "
     "apt-config dump 2>/dev/null | grep '^APT::Periodic::Unattended-Upgrade '; fi; "
     f"echo '[timers]'; for u in {_APT_TIMER} {' '.join(_DNF_TIMERS)}; do "
@@ -100,12 +105,26 @@ def kernel_reboot_pending(running: str, installed: List[str]) -> Optional[str]:
     return None
 
 
+def _freebsd_reboot(sections: Dict[str, List[str]]) -> Optional[Tuple[bool, Optional[str]]]:
+    """FreeBSD's answer from freebsd-version, or None on any other system."""
+    installed = (sections.get("freebsd-kernel") or [""])[0]
+    running = (sections.get("freebsd-running") or [""])[0]
+    if not (installed and running):
+        return None
+    if installed != running:
+        return True, f"kernel {installed} installed, {running} running"
+    return False, None
+
+
 def _reboot(sections: Dict[str, List[str]]) -> Tuple[Optional[bool], Optional[str]]:
     if "reboot-required" in sections:
         return True, f"{_REBOOT_FILE} is present"
     needs = sections.get("needs-restarting")
     if needs and needs[0] == "1":
         return True, "needs-restarting -r reports a reboot"
+    freebsd = _freebsd_reboot(sections)
+    if freebsd is not None:
+        return freebsd
     running = (sections.get("kernel") or [""])[0]
     modules = sections.get("modules") or []
     newer = kernel_reboot_pending(running, modules) if running and modules else None