Store `way_id` values for all edges

[danpat]

For debugging, it's very handy to be able to quickly cross-reference OSM. Currently, you have to do this manually using coordinates - get the location of the issue from OSRM, then browse to that location in OSM to get the way tag information.

I propose a new osrm-extract flag called --save-way-ids. When enabled, this will create a new, optional datafile called .osrm.edge_ways. At runtime, this file can be optionally mmap-ed, and data returned with annotations=ways and as a property on edges in the debug tiles.

Related: https://github.com/Project-OSRM/osrm-backend/issues/5104