Add ability to make public network shared

In some cases it might be required to have shared network for tempest
test. A good example might be trove test that assume having that.

Change-Id: I359c7caafc515ff2db0989e04fb0bc33ab843ba8

defaults/main.yml

@@ -220,6 +220,7 @@ tempest_public_subnet_cidr: "10.1.13.0/24"
 # tempest_public_subnet_gateway_ip:
 tempest_public_net_provider_type: "flat"
 tempest_public_net_physical_name: "physnet1"
+tempest_public_net_shared: False
 # tempest_public_net_seg_id:
 tempest_public_router_external: "True"
 # Example allocation range:

tasks/tempest_resources.yml

@@ -153,6 +153,7 @@
       segmentation_id: "{{ tempest_public_net_seg_id | default(omit) }}"
       external: "{{ tempest_public_router_external }}"
       project: "{{ keystone_demo_tenant_id }}"
+      shared: "{{ tempest_public_net_shared }}"
       subnets:
         - name: "{{ tempest_public_subnet_name }}"
           cidr: "{{ tempest_public_subnet_cidr }}"