Add the group and role checks API in tempest

Group and Role checks API does not exist api client and test.
Add this for normal API test.

Change-Id: I9146f9040f32e371154f96e72db6416ca0c34bab
Closes-bug: #1523368
diff --git a/tempest/api/identity/admin/v3/test_groups.py b/tempest/api/identity/admin/v3/test_groups.py
index e022023..df01074 100644
--- a/tempest/api/identity/admin/v3/test_groups.py
+++ b/tempest/api/identity/admin/v3/test_groups.py
@@ -76,8 +76,10 @@
         # list users in group
         group_users = self.groups_client.list_group_users(group['id'])['users']
         self.assertEqual(sorted(users), sorted(group_users))
-        # delete user in group
+        # check and delete user in group
         for user in users:
+            self.groups_client.check_group_user_existence(
+                group['id'], user['id'])
             self.groups_client.delete_group_user(group['id'], user['id'])
         group_users = self.groups_client.list_group_users(group['id'])['users']
         self.assertEqual(len(group_users), 0)