fix(FollowRouteControlStrategy): Add RouteStrategy

Till now it was is open how a simulator should plan a route for given
waypoints. This behavior is fixed by introducing a RouteStrategy,
following the specification of OpenSCENARIO 1.2.

Closes #14

Signed-off-by: Rene Paris <rene.paris@in-tech.com>

MantleAPI/include/MantleAPI/Traffic/control_strategy.h

@@ -49,6 +49,15 @@ enum class ControlStrategyType
   kPerformLaneChange
 };
 
+/// @brief Defines how a route should be calculated
+enum class RouteStrategy
+{
+  kUndefined = 0,
+  kFastest,
+  kLeastIntersections,
+  kShortest
+};
+
 struct ControlStrategy
 {
   virtual ~ControlStrategy() = default;
@@ -145,6 +154,7 @@ struct FollowRouteControlStrategy : public ControlStrategy
   }
 
   std::vector<mantle_api::Vec3<units::length::meter_t>> waypoints;
+  RouteStrategy route_strategy{RouteStrategy::kUndefined};
 };
 
 enum class Dimension