Added Osrm to route builder for custom route adapters

[Archdoog]

• Adds method to createRouteFromOsrm to simplify import for custom route adapters that use OSRM (e.g. valhalla-mobile)
• Revises OsrmResponseParser to use new route creation method. Note: this architecture bundles the via_waypoints and waypoints into each Route init. While this is technically extra work, I figured it was the lesser cost of duplicating and creating extra function entry points for pre-built waypoints.
• Renames ReponseParserError to OsrmParserError. I'd be interested in better naming here, but given some of the error naming TODOs, figured we might want to strategize more globally where we're going with an error system. Especially how tidily rust handles error translation.