rmf_geometry_testbed: Interactive tests for testing collision detection, collision primitives approximation

1. Create a new colcon workspace
2. Clone this repo
3. Clone rmf repositories https://github.com/open-rmf/rmf_utils.git, https://github.com/open-rmf/rmf_traffic.git
4. Clone fcl 6.0 https://github.com/flexible-collision-library/fcl.git
5. Clone https://github.com/SFML/SFML
6. Clone https://github.com/eliasdaler/imgui-sfml.git
7. Clone the version of https://github.com/ocornut/imgui.git mentioned in the previous step (at the time of this writing, v1.80)
8. go into your imgui directory and do touch COLCON_IGNORE
9. colcon build --cmake-args -DBUILD_SHARED_LIBS=ON -DIMGUI_DIR=<your colcon workspace>/src/imgui

Then you can start running interactive tests in the ./build/rmf_geometry_testbed/ directory