Apply backward waypoints to lane_select

Implemented feature

Enable to search for a target point on the backward waypoints.

Description

This MR is able to handle negative speeds with waypoints in lane_select.

Related issue is #8 (closed) .

(Most of #8 (closed) must be merged to allow backward driving.)

To merge this MR, we must first merge MR common!29 (merged).

Implementation considerations

The waypoint that satisfies the following conditions is selected as the next target point (closest_waypoint).

• (1) Waypoint in front of the vehicle.
• (2) Waypoints with difference from vehicle direction less than 90 deg.

(1) is valid only when the vehicle moves forward. When reversing, it is necessary to select a waypoint behind the vehicle.

The function of identifying whether the waypoint is for forward or reverse is based on the MR common!29 (merged).

How to test

Please check if the test code passes.