add ros intermediate exercises

...n_scripts/ros/ros_intermediate/ros_intermediate_1_eval.py

...n_scripts/ros/ros_intermediate/ros_intermediate_2_eval.py

...ion_scripts/ros/ros_intermediate/ros_intermediate_1.ipynb

...ion_scripts/ros/ros_intermediate/ros_intermediate_2.ipynb

..._ws/src/learn_environment/task_pool/task_definitions.json