Fix urdf file, create urdf simulation for 2dof_2 and rename launch files

...t_1dof/launch/simple_robot_rviz_simulation_1dof_launch.py

ros2_ws/src/simple_robot_1dof/setup.py

...t_2dof/launch/simple_robot_rviz_simulation_2dof_launch.py

ros2_ws/src/simple_robot_2dof/setup.py

..._2dof/simple_robot_2dof/forward_kinematics_node_2dof_1.py

..._2dof/simple_robot_2dof/forward_kinematics_node_2dof_2.py

ros2_ws/src/simple_robot_2dof/urdf/simple_robot.urdf

...matik/simple_robot_inverse_kinematik/inverse_kinematik.py