Rename get_or_add_user_role

get_or_add_user_role is specific to adding a role on a project.
Rename it to get_or_add_user_project_role to allow room for adding a
domain specific role function.

Change-Id: I999308098d22be9800578ae67144a3b687fbc3be
diff --git a/lib/tempest b/lib/tempest
index 777d03e..560ab1b 100644
--- a/lib/tempest
+++ b/lib/tempest
@@ -505,7 +505,7 @@
         # between two regular users in separate tenants
         get_or_create_project alt_demo
         get_or_create_user alt_demo "$ADMIN_PASSWORD" "alt_demo@example.com"
-        get_or_add_user_role Member alt_demo alt_demo
+        get_or_add_user_project_role Member alt_demo alt_demo
     fi
 }