calico add support for container ip forwarding setting (#8184)

roles/network_plugin/calico/templates/cni-calico.conflist.j2

@@ -38,6 +38,11 @@
         "ipv4_pools": ["{{ calico_pool_cidr | default(kube_pods_subnet) }}"]
       },
 {% endif %}
+{% if calico_allow_ip_forwarding %}
+      "container_settings": {
+        "allow_ip_forwarding": true
+      },
+{% endif %}
 {% if (calico_feature_control is defined) and (calico_feature_control|length > 0) %}
       "feature_control": {
         {% for fc in calico_feature_control -%}