Gracefully handle unknown tenantId with

[porcellus]

We currently error out if: dynamicLoginMethods is enabled but getTenantId returns an unknown id.
We should:

• Show a sensible error in the console
• Show the access denied screen with a specific message like we do here

Reproduction:

• start & open default test app
• run in browser console:

localStorage.setItem("usesDynamicLoginMethods", "true");
localStorage.setItem("mockTenantId", "asdf");

• open/refresh auth screen