Initial patch to add barbican rbac tests

This adds initial RBAC tests for secrets

Change-Id: Ib79eed6886839d1b7848c991bd64e82595c6c32e
diff --git a/barbican_tempest_plugin/tests/api/base.py b/barbican_tempest_plugin/tests/api/base.py
index 7256a10..2599480 100644
--- a/barbican_tempest_plugin/tests/api/base.py
+++ b/barbican_tempest_plugin/tests/api/base.py
@@ -84,6 +84,11 @@
         cls.quota_client = os.secret_v1.QuotaClient(service='key-manager')
 
     @classmethod
+    def setup_credentials(cls):
+        super().setup_credentials()
+        cls.os_primary = getattr(cls, f'os_{cls.credentials[0]}')
+
+    @classmethod
     def resource_setup(cls):
         super(BaseKeyManagerTest, cls).resource_setup()
         for resource in RESOURCE_TYPES: