Fix and simplify routing for creator/presentation question carousel
The routing logic for the carousel got quite complex. A lot of variables influence the actual behavior: LAST_INDEX (localStorage), route params, and the flag for presentation mode. The routing currently also has a noticeable effect: The first question is always shown for a brief moment and then the view transitions to the question for the selected index.
Suggestion
Reduce the number of variables. Does presentation mode need to affect the routing? We could just always use the route param if it is set and only check local storage for the /statistics route w/o an index.
- /statistics => check localStorage, and then navigate to /statistics/{index}, use 1 as a fallback
- /statistics/{index} => use the index as is, don't do any magic
This behavior would be similar to the participant's carousel which doesn't use localStorage but instead checks for the first unanswered question. The the auto navigation to the first unanswered question is only performed if no index is set.