Properly update sub model with type and modifier (#384)

The type and modifier fields are part of the official MapBox spec for
allowed sub fields. In practice, they are mostly unused in favor of
using them inside of components instead, but they are allowed and we are
already parsing them, so this patch properly propagates them.

common/ferrostar/src/routing_adapters/osrm/mod.rs

@@ -219,9 +219,9 @@ impl RouteStep {
                 }),
                 sub_content: banner.sub.as_ref().map(|sub| VisualInstructionContent {
                     text: sub.text.clone(),
-                    maneuver_type: None,
-                    maneuver_modifier: None,
-                    roundabout_exit_degrees: None,
+                    maneuver_type: sub.maneuver_type,
+                    maneuver_modifier: sub.maneuver_modifier,
+                    roundabout_exit_degrees: sub.roundabout_exit_degrees,
                     lane_info: {
                         let lane_infos: Vec<LaneInfo> = sub
                             .components