can not generate path from co-located lanes

[beyzanurkaya]

The current route_handler package is considered as the start_lanelet, the lane closest to the road_lanelets_ at the given start checkpoint for path generation. However, this method can cause problems with overlapped lanes.

For example, these two lanes overlap as shown. Since the next_lanes they have are different from each other, different paths are generated to the given goal pose, and sometimes even the path is not created if the appropriate next_lane is not available.

In this case, all current_lanes should be checked and considered as start_lane, from which the shortest path can be generated.

What do you think about this idea?

[mehmetdogru]

@beyzanurkaya we can resolve the discussion since autowarefoundation/autoware_universe#4013 is merged