feat(talos): Add option to specify other gateway (#1316)

* feat(talos): Add option to specify other gateway

* Renamed to default_gateway and add BGP config

* Update config.sample.yaml

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Co-authored-by: Devin Buhl <onedr0p@users.noreply.github.com>

bootstrap/templates/kubernetes/apps/kube-system/cilium/app/cilium-bgp.yaml.j2

@@ -17,7 +17,11 @@ spec:
           peerASN: {{ distribution.talos.bgp.peer_asn }}
         {% endfor %}
         {% else %}
+        {% if nodes.default_gateway %}
+        - peerAddress: "{{ nodes.default_gateway }}/32"
+        {% else %}
         - peerAddress: "{{ nodes.host_network | nthhost(1) }}/32"
+        {% endif %}
           peerASN: {{ distribution.talos.bgp.peer_asn }}
         {% endif %}
       serviceSelector: