EZP-23366 - Correct active view service value not set correctly in the PlatformUI app

https://jira.ez.no/browse/EZP-23366

Corrected the value of active view service when the app is loading a new view and its service.
I understood that but what I mention this thread is that in the case where the route does not have a view service, the activeViewService attribute is not updated so the state of the application is not consistent, so you need to set it to something reflecting the fact that there's no active view service. And, in any case, the unit tests are missing!