[feature request] Add a gazebo based example to this project to showcase urdf -> sdf loader

[rydb]

This project needs an example to showcase the "launch_gazebo_world" doing something other then opening an empty world and loading the model in it.

Perhaps having a robot navigate from point A -> B via point and click would work well. Will need help implementing this since I'm new to gazebo

This demo:

• 1: should not require the user to manually edit an .sdf file to use. We may need to add a new mechanism for editing gazebo world files to simple_run in order to avoid this.
• 2: should only require the user to read the simple_run_caller.py and another script inside model_pkg which stores the point & click functionality to know "what" is happening
• 3: should have documentation alongside it showing how to run it