simplify map matching gps accuracy input and update best practices documentation

over in #3854 we discovered the documentation is lacking when it comes to properly informing users how to get the best results out of the api. to that end, in summary, we should simplify the parsing of accuracy/radius for input locations (basically deprecate accuracy and simply put it into the radius parameter). this might be a bit complicated because we both a limit and a user input to worry about but we should take a minute to see if we can make it easier. after we've done that clean up we should update to docs to mention that best results are had when users set per point gps accuracies (usually horizontal accuracy reported from android and ios apis and usually multiplying them by 3). more info in this comment: https://github.com/valhalla/valhalla/issues/3854#issuecomment-1333850207