T6701 Added ability to disables the container DNS

Add ability to set the container network with a disable-dns setting
to disable the DNS plugin that is on be default.

T6701: Containers - disable container network built in DNS plugin

interface-definitions/container.xml.in

@@ -519,6 +519,12 @@
               <multi/>
             </properties>
           </leafNode>
+          <leafNode name="disable-dns">
+            <properties>
+              <help>Disables the DNS plugin for this network</help>
+              <valueless/>
+            </properties>
+          </leafNode>
           #include <include/interface/vrf.xml.i>
         </children>
       </tagNode>

src/conf_mode/container.py

@@ -421,6 +421,10 @@ def generate(container):
                     'driver': 'host-local'
                 }
             }
+
+            if 'disable_dns' in network_config:
+                tmp['dns_enabled'] = False
+
             for prefix in network_config['prefix']:
                 net = {'subnet': prefix, 'gateway': inc_ip(prefix, 1)}
                 tmp['subnets'].append(net)