Minor: Not sure if it's an issue, but this requires the view to have some "smarts" and that feels a tiny bit wrong. Feels like we should be able to have an `MKDistanceFormatter` at a higher level that gets configured once rather than creating one every time we re-compute a `ManeuverInstructionView`.
Background
_Originally posted by @ianthetechie in https://github.com/stadiamaps/ferrostar/pull/71#discussion_r1542292427_
Resolution
Discussed on slack; we'll make a generic protocol for distance formatters and allow one to be set by the user for greater configurability.