highway=turning_circle should be used for u-turns

[MarcelloPerathoner]

Feature

OSRM should use nearby turning circles for u-turns.

Current situation

OSRM ignores perfectly good turning opportunities and instead routes you literally through the woods, like here: (Note that there is no road where OSRM tells you to turn!)

https://map.project-osrm.org/?z=18&center=46.562307%2C11.718265&loc=46.562099%2C11.718770&loc=46.562176%2C11.718206&loc=46.562121%2C11.718603&hl=en&alt=0&srv=0

Maybe duplicate of: #620, but that one was closed without proper resolution and I'm not allowed to reopen it.