Added conf option to scope wg hub to right netns (#289)

This change is to add the 'create_hub_in_root_netns' boolean option
designed to scope the wireguard hub creation to the root network
namespace instead of the project network namespace if set to True. 

To set, add the following option to the site's defaults:
```
neutron_wireguard_create_hub_in_root_netns: True/False
```

kolla/node_custom_config/neutron/ml2_conf.ini

@@ -73,4 +73,5 @@ key_file = /etc/neutron/ssh/id_{{ switch.name }}
 {% if enable_neutron_wireguard | bool %}
 [wireguard]
 endpoint = {{ neutron_wireguard_hub_endpoint }}
+create_hub_in_root_netns = {{ neutron_wireguard_create_hub_in_root_netns }}
 {% endif %}