planning: adjust slowdown profile parameters and allow em planner to return slowdown trajectory in case of error.

Planning: fixed a issue in reference line smoother. The lateral direction is the direction the adc drives

Planning: improved st_boundary_mapper by making mapping independent on path_point resolution in path_data. (#1436)

alignment

Planning: (1) adjust lateral/longitudinal bound in reference_line_smoother to provide near to center reference lines; (2) adjust the speed lower bound from 0.0 to 1e-12 to avoid double precision issue in qp_st_speed_graph.

based on distance.