feat: Snap S overshooting objects and signals to the road's end

Previously, any object/signal S-coordinate exceeding a road's length caused a hard failure. This PR introduces a configurable s_overshoot_tolerance (from s_overshoot_tolerance_in_m UserSetting defined in gt-gen-core!500 (merged)) that snaps slightly-overshooting S values to the road's end and sending a warning message, while still throwing for overshoots beyond the configured tolerance.

Note: Road length is calculated from the sum of its geometries because it is currently not enforced that xml_road.length has to match it.