Major QR feature improvements

[vanjo9800]

The QR code scanning feature started out as a simple idea for stats, but ended up being our major passport system for the event. That is why I recommend to look again at this feature and enhance it as there were some problems during the event.

Currently the feature is stateless: A QR code is scanned, validated using RegEx, sent to the backend, validated again and added to an array attribute in the user profile.

We can improve this by:

• Adding a timestamp of when the code was scanned
• Serving live stats of who has scanned a code (+ export as CSV would be definitely useful) on the committee admin page
• Maybe making the QR codes links to our dashboard, so they can be scanned from any application and just lead the applicant to the dashboard