feat(avoidance): add new flag to use freespace in avoidance module (autowarefoundation#818)

Signed-off-by: satoshi-ota <satoshi.ota928@gmail.com>

Author: satoshi-ota

autoware_launch/config/planning/scenario_planning/lane_driving/behavior_planning/behavior_path_planner/avoidance/avoidance.param.yaml

@@ -19,6 +19,7 @@
       use_opposite_lane: true
       use_intersection_areas: true
       use_hatched_road_markings: true
+      use_freespace_areas: true
 
       # for debug
       publish_debug_marker: false