[ROS2] First prototype of Real Follow Person exercise

[Carlosalpha1]

Hi, I have added all files to run Real Follow Person exercise:

• Web template files
• modification of instructions.json and manager-4.0.py to run the exercise. The exercise doesn't use Gazebo, therefore it was necessary to modify the manager.py to launch only ROS instructions, the exercise.py and the console.
• The db.sqlite3 has been modified to incorporate the exercise

This pull-request solves the issue #1580

Instructions to launch the RADI:

docker run -it --rm --device /dev/ttyUSB0 --device /dev/ttyUSB1 --device /dev/video0 --name prueba -p 8000:8000 -p 2303:2303 -p 1905:1905 -p 8765:8765 -p 6080:6080 -p 1108:1108 <your_test_radi>

• /dev/ttyUSB0: Kobuki base of TurtleBot2
• /dev/ttyUSB1: RPLIDAR
• /dev/video0: Camera