Update host_aggregate to be compatible with new sdk

- Change the implementation to use the proxy layer
- Update the module to return an aggregate object
- Adds a role to test the module

Change-Id: I6a98ba8466863b41fc996855fd12cf9f3097abe0

ci/roles/host_aggregate/defaults/main.yml

@@ -0,0 +1,11 @@
+expected_fields:
+  - availability_zone
+  - created_at
+  - deleted_at
+  - hosts
+  - id
+  - is_deleted
+  - metadata
+  - name
+  - updated_at
+  - uuid