Separate launch files by use case for better maintainability

[darthegg]

The current launch file structure is becoming harder to manage as multiple responsibilities are mixed together.
We should separate launch files by use case and execution environment to make them easier to maintain, reuse, and extend.

Proposed examples

1. Lidar SLAM launch file based on slam_toolbox
2. Realsense D455 + RTAB-Map launch file for rosbag play
3. Realsense D455 + RTAB-Map launch file for real camera input