Federated authentication via ECP functional tests

Adds a first test for the federated authentication feature. It handles
first the authentication using the SAML2 ECP profile.

The tests cleanup have some issues, see related bug.

Related-Bug: 1642692
Change-Id: I3b393a695c6d9f846efdaf302c1beea34e6bd54b
diff --git a/keystone_tempest_plugin/clients.py b/keystone_tempest_plugin/clients.py
index a72c9f5..9865b91 100644
--- a/keystone_tempest_plugin/clients.py
+++ b/keystone_tempest_plugin/clients.py
@@ -18,6 +18,8 @@
     mapping_rules_client)
 from keystone_tempest_plugin.services.identity.v3 import (
     service_providers_client)
+from keystone_tempest_plugin.services.identity.v3 import auth_client
+from keystone_tempest_plugin.services.identity.v3 import saml2_client
 
 from tempest import clients
 
@@ -27,12 +29,14 @@
     def __init__(self, credentials, service=None):
         super(Manager, self).__init__(credentials, service)
 
+        self.auth_client = auth_client.AuthClient(self.auth_provider)
         self.identity_providers_client = (
             identity_providers_client.IdentityProvidersClient(
                 self.auth_provider))
         self.mapping_rules_client = (
             mapping_rules_client.MappingRulesClient(
                 self.auth_provider))
+        self.saml2_client = saml2_client.Saml2Client()
         self.service_providers_client = (
             service_providers_client.ServiceProvidersClient(
                 self.auth_provider))