Use last known car position as start position to plan a trip

🚧 THIS IS A TICKET MIGRATED FROM UPVOTY. The original ticket and comments will be available for a limited time over at:
https://abrp.upvoty.com/b/request-a-feature/use-last-known-car-position-as-start-position-to-plan-a-trip/
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As a user, I would like to use the last known car position as start position so that I can plan my future trip when I'm in the train.

ABRB knows the last car position, displayed with a grey triangle. The longitude and latitude can be found as well in the car detail view.

In the "from" position when planing a trip, next to "home" or "work", it would be great to have "car position", which can be different from my current GPS position.