custom configs

[morganherlocker]

We currently support default configs for cars, bikes, and scooters, however, I often find myself needing to tweak various values to test edge cases. For example, I may need to simulate a scooter company that has more frequent breakdowns than usual or a taxi company that uses lofi GPS units.

This proposal would add support for a file path as the config, with the existing keywords maintained.

trip-simulator --config bike
trip-simulator --config ./bike-with-faulty-wheels.json