Introduce scope_types in os-admin-password
Introduce scope_types in os-admin-password

oslo.policy introduced the scope_type feature which can
control the access level at system-level and project-level.
 - https://docs.openstack.org/oslo.policy/latest/user/usage.html#setting-scope
 - http://specs.openstack.org/openstack/keystone-specs/specs/keystone/queens/system-scope.html

Appropriate scope_type for nova case:
- https://specs.openstack.org/openstack/nova-specs/specs/ussuri/approved/policy-defaults-refresh.html#scope

This commit introduce scope_type for os-admin-password API policies
as 'system' and 'project'.

Also adds the test case with scope_type enabled and verify we
pass and fail the policy check with expected context.

Partial implement blueprint policy-defaults-refresh

Change-Id: I859dca0acdd76fa385014bc96b2f24df522be4f4

klmitch/nova,klmitch/nova,openstack/nova,openstack/nova,klmitch/nova,klmitch/nova,mahak/nova,mahak/nova,mahak/nova,openstack/nova