[sim] add new walli urdf

[mrinalTheCoder]

Description

This PR does the following:

• Updated URDF for WALL-II in sim.
• Updated ROS2 control config for sim.
• Cleanup of (many) unused files

Fixes #254

Testing Steps (if relevant)

Test Case 1

1. Run bringup_simulation.launch.py. Wall-II should spawn in.
2. Set the control mode to teleop (ros2 topic pub -r 1 /cmd_vel_mode std_msgs/msg/String "{data: 'teleop'}")
3. Wall-II should respond to Xbox controller input.

Expectation:

Self Checklist

• I have formatted my code using ament_uncrustify --reformat
• I have tested that the new behavior works