This patch makes the following changes:
- Adds **params to list_endpoints since identity v3 endpoints
can be filtered by "interface" and "service_id" [0]
- Enhance v3 endpoint API tests to check that filtering by
such params works correctly.
[0] https://developer.openstack.org/api-ref/identity/v3/#list-endpoints?expanded=list-endpoints-detail
Change-Id: I133485db6f9a13d71595d43547f0dc9ea6ca0584