Initial MOTIS backend support

This patch adds support for checkins using MOTIS backends
using the Travel::Status::MOTIS module.

With this travelynx supports the two services currently
exposed by the module, RNV for local transit in Mannheim,
Germany and surrounding cities and transitous for worldwide
crowdsourced tranit feeds.

This implementation supports realtime predictions,
cancellations and polylines as well as custom route colors
if available.

As MOTIS doesn't expose names of indivial trips currently,
displaying transports is mostly limited to route names.

MOTIS uses strings for stop ids, based on the used GTFS
source feeds. As travelynx's data model currently assumes
interger station ids, this patch adds a mapping table
to the database.

This patch assumes support for MOTIS in db-fakedisplay.

Note that while träwelling has migrated to tranitous fully
sync remains unsupported for now.

See https://github.com/Traewelling/traewelling/issues/3345