Add support for opposite approach request parameter (#6842)

* Added approach on the opposite side of the road.

* Additional test and docs coverage for opposite approach

---------

Co-authored-by: Aleksandrs Saveljevs <Aleksandrs.Saveljevs@gmail.com>

docs/nodejs/api.md

@@ -63,7 +63,7 @@ Returns the fastest route between two or more coordinates while visiting the way
     -   `options.geometries` **[String](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String)** Returned route geometry format (influences overview and per step). Can also be `geojson`. (optional, default `polyline`)
     -   `options.overview` **[String](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String)** Add overview geometry either `full`, `simplified` according to highest zoom level it could be display on, or not at all (`false`). (optional, default `simplified`)
     -   `options.continue_straight` **[Boolean](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Boolean)?** Forces the route to keep going straight at waypoints and don't do a uturn even if it would be faster. Default value depends on the profile.
-    -   `options.approaches` **[Array](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Array)?** Keep waypoints on curb side. Can be `null` (unrestricted, default) or `curb`.
+    -   `options.approaches` **[Array](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Array)?** Restrict the direction on the road network at a waypoint, relative to the input coordinate. Can be `null` (unrestricted, default), `curb` or `opposite`.
                          `null`/`true`/`false`
     -   `options.waypoints` **[Array](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Array)?** Indices to coordinates to treat as waypoints. If not supplied, all coordinates are waypoints.  Must include first and last coordinate index.
     -   `options.format` **[String](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String)?** Which output format to use, either `json`, or [`flatbuffers`](https://github.com/Project-OSRM/osrm-backend/tree/master/include/engine/api/flatbuffers).
@@ -101,7 +101,7 @@ Note: `coordinates` in the general options only supports a single `{longitude},{
     -   `options.generate_hints` **[Boolean](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Boolean)** Whether or not adds a Hint to the response which can be used in subsequent requests. (optional, default `true`)
     -   `options.number` **[Number](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Number)** Number of nearest segments that should be returned.
         Must be an integer greater than or equal to `1`. (optional, default `1`)
-    -   `options.approaches` **[Array](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Array)?** Keep waypoints on curb side. Can be `null` (unrestricted, default) or `curb`.
+    -   `options.approaches` **[Array](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Array)?** Restrict the direction on the road network at a waypoint, relative to the input coordinate. Can be `null` (unrestricted, default), `curb` or `opposite`.
     -   `options.format` **[String](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String)?** Which output format to use, either `json`, or [`flatbuffers`](https://github.com/Project-OSRM/osrm-backend/tree/master/include/engine/api/flatbuffers).
     -   `options.snapping` **[String](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String)?** Which edges can be snapped to, either `default`, or `any`.  `default` only snaps to edges marked by the profile as `is_startpoint`, `any` will allow snapping to any edge in the routing graph.
 -   `callback` **[Function](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Statements/function)** 
@@ -141,7 +141,7 @@ Optionally returns distance table.
     -   `options.sources` **[Array](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Array)?** An array of `index` elements (`0 <= integer < #coordinates`) to use
                                          location with given index as source. Default is to use all.
     -   `options.destinations` **[Array](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Array)?** An array of `index` elements (`0 <= integer < #coordinates`) to use location with given index as destination. Default is to use all.
-    -   `options.approaches` **[Array](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Array)?** Keep waypoints on curb side. Can be `null` (unrestricted, default) or `curb`.
+    -   `options.approaches` **[Array](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Array)?** Restrict the direction on the road network at a waypoint, relative to the input coordinate.. Can be `null` (unrestricted, default), `curb` or `opposite`.
     -   `options.fallback_speed` **[Number](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Number)?** Replace `null` responses in result with as-the-crow-flies estimates based on `fallback_speed`.  Value is in metres/second.
     -   `options.fallback_coordinate` **[String](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String)?** Either `input` (default) or `snapped`.  If using a `fallback_speed`, use either the user-supplied coordinate (`input`), or the snapped coordinate (`snapped`) for calculating the as-the-crow-flies distance between two points.
     -   `options.scale_factor` **[Number](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Number)?** Multiply the table duration values in the table by this number for more controlled input into a route optimization solver.
@@ -298,7 +298,7 @@ Right now, the following combinations are possible:
     -   `options.roundtrip` **[Boolean](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Boolean)** Return route is a roundtrip. (optional, default `true`)
     -   `options.source` **[String](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String)** Return route starts at `any` or `first` coordinate. (optional, default `any`)
     -   `options.destination` **[String](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String)** Return route ends at `any` or `last` coordinate. (optional, default `any`)
-    -   `options.approaches` **[Array](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Array)?** Keep waypoints on curb side. Can be `null` (unrestricted, default) or `curb`.
+    -   `options.approaches` **[Array](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Array)?** Restrict the direction on the road network at a waypoint, relative to the input coordinate. Can be `null` (unrestricted, default), `curb` or `opposite`.
     -   `options.snapping` **[String](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String)?** Which edges can be snapped to, either `default`, or `any`. `default` only snaps to edges marked by the profile as `is_startpoint`, `any` will allow snapping to any edge in the routing graph.
 -   `callback` **[Function](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Statements/function)**