Stairs in the ROS 2 simulator

The simulation of the robot's ROS 2 stack now has the stair course, and the driving page switches between policies while the simulation runs.

• Lanes of 2, 3 and 4 cm steps with the layout of the printable course
• Physics advances in step with the control loop, so a busy computer slows the simulation without disturbing the controller
• Our stair policy crossed the 3 cm stairs in 5 of 5 runs