Link to bahn.expert on status detail page

[jeriox]

After checking in into a train myself or after viewing a checkin of another person that I want to pick up at a station, I often want to check the trains stops and current expected arrival time which is more accurate and up to date on bahn.expert. Currently, I need to paste the train number in bahn.expert or find the train from the departure board. It would be very handy to have a button on the status detail page that takes me to the journey of the train on bahn.expert

[DRSchlaubi]

Sadly bahn.expert doesn't accept hafas journey IDs anymore so this will be tricky

[jheubuch]

Can be done when Traewelling/traewelling#1704 is merged