[feat] Convert from OSM data (files or links)

[lgrd]

Need

r2gg can create a .osm from the pivot. And r2gg can read them to create osrm or valhalla data. But it can't convert an osm data to pivot.

Functionalities

• Download an osm file
• Convert an osm file to the pivot format
• Be able to make an entire generation from osm to pgr, osrm and valhalla

Tasks

• Update the generation file format
• Be sure of the CLI and its IO
• Code it
• Update and run tests
• Update docs (changelog and documentation directory) of this project
• Update contributing.md of this project
• Update contributing.md of Road2
• Update readme.md and docs of Road2

Code

// TODO