feat(path_generator): add parameters (see below)

  * This fix is for the following PR:
      autowarefoundation/autoware_core#227

Signed-off-by: Junya Sasaki <[email protected]>

Author: sasakisasaki

autoware_launch/config/planning/scenario_planning/lane_driving/behavior_planning/path_generator/path_generator.param.yaml

@@ -12,3 +12,5 @@
       search_distance: 30.0
       resampling_interval: 1.0
       angle_threshold_deg: 15.0
+    refine_goal_search_radius_range: 10.0  # [m]
+    search_radius_decrement: 1.0