Import firewall role from network repo

Move, actually.

roles/firewall/templates/networks.nft.j2

@@ -0,0 +1,9 @@
+{% for family, family_prefixes in vrf_prefixes | groupby('family.value') %}
+{% for vlan, vlan_prefixes in family_prefixes | groupby('vlan.vid') %}
+set {{ vlan_prefixes[0].vlan.name }}{% if family == 6 %}/6{% endif %} {
+    type ipv{{ family }}_addr; flags interval
+    elements = { {{ vlan_prefixes | map(attribute='prefix') | join(',') }} }
+}
+{% endfor %}
+
+{% endfor %}