Add launch files to smooth the ndt localization output

Description

Adds the launch files that connect the output of the ndt localizer to an ekf smoother. This MR builds on top of the NDT demo and adds a new demo launch file with additional config for the ekf smoother.

• Depends on !476 (merged)
• Depends on !521 (merged)
• Relates to #505 (closed)

Notes for Reviewer

For now there are the nodes to run the ekf smoothing on top of the ndt localization. The output of the ekf is not fed back to the localization node for initial guess. This can improve the robustness of the overall localization, but is left for the future. This MR is to prove that out EKF implementation can track the car.

Checklist

• Documentation was updated