feat: report the firewall's CARP addresses as virtual IPs

get_virtual_ips() reads every address bound to a CARP VHID -- the CARP
address and IP aliases on its VHID alike -- from
/api/interfaces/overview/export, with this node's CARP state, so the reading
says who holds each address. interfaces/vip_settings would list the same
addresses with each VHID's CARP password; it is not read.

vip_manager and keepalived are Linux mechanisms and are None here. Needs
napalm-device-types 4.10.0 (carp_virtual_ip).

netOrk #1121.

napalm_opnsense/virtual_ips.py

@@ -0,0 +1,63 @@
+"""The firewall's CARP addresses, read from its interface overview (netOrk #1121).
+
+``/api/interfaces/overview/export`` lists every address of an interface; one bound
+to a CARP VHID carries ``vhid`` and this node's CARP ``status``. That covers the
+CARP address itself and an IP alias bound to its VHID alike -- both float with the
+VHID's MASTER. An address without a VHID stays on this node and is no virtual IP.
+
+``interfaces/vip_settings/search_item`` would list the same addresses, but with
+each VHID's CARP password in it. The overview has none, so a secret never reaches
+the caller.
+
+What a state means (MASTER holds, BACKUP stands by) is the same on every CARP
+firewall: :func:`napalm_device_types.virtual_ips.carp_virtual_ip`.
+"""
+
+from __future__ import annotations
+
+import ipaddress
+from typing import Any
+
+from napalm_device_types.models import VirtualIpDict
+from napalm_device_types.virtual_ips import carp_virtual_ip
+
+
+def _interfaces(overview: Any) -> list[Any]:
+    """The interface list, whether the answer is the list or wraps it."""
+    if isinstance(overview, dict):
+        return overview.get("interfaces") or []
+    if isinstance(overview, list):
+        return overview
+    raise ValueError(f"unexpected interface overview: {type(overview).__name__}")
+
+
+def carp_addresses(overview: Any) -> list[VirtualIpDict]:
+    """Every address bound to a CARP VHID in *overview*, sorted by address.
+
+    :raises ValueError: when the answer is neither the interface list nor wraps it.
+    """
+    entries: list[VirtualIpDict] = []
+    for interface in _interfaces(overview):
+        if not isinstance(interface, dict):
+            continue
+        identifier = interface.get("identifier") or ""
+        for family in ("ipv4", "ipv6"):
+            for address in interface.get(family) or []:
+                if not isinstance(address, dict) or not address.get("vhid"):
+                    continue
+                entry = carp_virtual_ip(
+                    address=str(address.get("ipaddr") or ""),
+                    prefix_length=None,
+                    vhid=address.get("vhid"),
+                    state=address.get("status"),
+                    instance=interface.get("description") or identifier,
+                    interface=interface.get("device") or identifier or None,
+                )
+                if entry is not None:
+                    entries.append(entry)
+    return sorted(entries, key=_order)
+
+
+def _order(entry: VirtualIpDict) -> tuple[int, int]:
+    address = ipaddress.ip_address(entry["address"])
+    return address.version, int(address)