Extend ROS topics to accept integer arrays for state representation

When using the EMAM2Middleware to generate a reinforcement learning agent, which is connected via ros-gym to python, defining the state as an integer array in python leads to an error, because the middleware initializes the state topic in ROS as Float32MultiArray, regardless of the definition in the python files.

This file implements Int32MultiArray as the default topic type for the state.

To resolve this issue, it would be necessary to automatically switch between the Float- and Integer-representation for the ROS state topic. This can be implemented in the template file for the environment of the agent.