Code refactor

[haritsahm]

Changes

• Add a collision to car's body
• Add keyboard_command_callback to command_multiplexer.py for teleoperating using keyboard
• Remove veolcity scaling in src/control_plugin.py#L134 in convert the input velocity (in reference/local frame) to joint speed (wheel rotation in rad/s)
• Remove car_x.access and replace with singular car_controller.launch with arguments
• Refactor one_car.launch.xml to car_gazebo.launch to specify a car's gazebo configuration
• Refactor vehicle_class.launch.xml to car_spawner.launch for launching a car with specific configuration
• Publish a rosparam car_x/init_pose that contains the spawn position in [x_pos, y_pos, z_pos] to replace offset and easier to use across packages
• Add the old simulator.launch and race_track world from previous tutorial
• Add an offset (-9, -5) to new race-track map map/race_track.yaml#L3 to align the center of map with track origin
• Change speed and angle limit in scripts/keyboard_teleop.py#L17
• Change odom_frame in src/control_plugin.py#L45 to car_x_odom to separate multiple car odometry when using the same map (found this bug in multi_teb tutorial)
• Replace racecar_reset_state function in src/set_racecar_state.py#L31 using rossrv instead of rosparam
• Fix laser scan tf tree (link position) in base_laser_link static transform publisher. The laser scan should be at the top of the car or in the laser 3d rendering, but somehow it is on the ground level between the wheels)
• Replace #!/usr/bin/env python with #!/usr/bin/env python3 since I'm using Noetic.

Snapshots

[varundevsukhil]

Thanks for the effort @haritsahm.

We will review and merge once we have tested on our machines.

[haritsahm]

Let me know if I need to change anything. I will also open a PRs for the tutorials and pure-pursuit