Namex UI: login fails if already logged in with non-IDIR

**Use case**
As a staff user,
Given I want to access namex UI,
When I am already logged in as a regular user in a different browser tab,
Then my login to namex UI fails silently.

**Impact**
This prevents a user from using a BCROS web app as a regular user while at the same time trying to access namex UI.

**Workarounds**
1. login to namex UI in Incognito mode
2. login to namex UI in a different browser

**Potential improvements**
These do not fix the issue but give the user more information.

1. use common BCROS header/login mechanism
2. let staff user know why their namex UI login fails