Enable users to define the policy rules on server group policy
to meet more advanced policy requirement. This microversion
brings the following changes in server group APIs:
* Add ``policy`` and ``rules`` fields in the request of POST
``/os-server-groups``.
* The ``policy`` and ``rules`` fields will be
returned in response body of POST, GET ``/os-server-groups``
API and GET ``/os-server-groups/{server_group_id}`` API.
* The ``policies`` and ``metadata`` fields have been removed
from the response body of POST, GET ``/os-server-groups`` API
and GET ``/os-server-groups/{server_group_id}`` API.
Part of blueprint: complex-anti-affinity-policies
Change-Id: I6911e97bd7f8df92511e90518dba21c127e106a5