Add scope_types to project endpoint policies
Add scope_types to project endpoint policies

This commit gives all project endpoint policies a scope type of
`system` since endpoints are system-level resources.

From now on, a warning will be logged when a project-scoped token is
used to manage project endpoint associations. Operators will have the
option to require system-scoped tokens for these policies by enabling
oslo.policy's `enforce_scope` configuration option, which will result
in an HTTP Forbidden exception when mismatching scope is detected.

Change-Id: I23b12f9a4cfbb124a6ea2cc55b5c0ccb2d463ae8

mahak/keystone,openstack/keystone,openstack/keystone,openstack/keystone,mahak/keystone,mahak/keystone