Adds **params to v3 list_endpoints

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
diff --git a/releasenotes/notes/add-params-to-identity-v3-list-endpoints-958a155be4e17e5b.yaml b/releasenotes/notes/add-params-to-identity-v3-list-endpoints-958a155be4e17e5b.yaml
new file mode 100644
index 0000000..46f3b49
--- /dev/null
+++ b/releasenotes/notes/add-params-to-identity-v3-list-endpoints-958a155be4e17e5b.yaml
@@ -0,0 +1,6 @@
+---
+features:
+  - |
+    The ``list_endpoints`` method of the v3 ``EndPointsClient`` class now has
+    an additional ``**params`` argument that enables passing additional
+    information in the query string of the HTTP request.