Avoid calling write in inactive state

[christophfroehlich]

After looking at the code, I believe this is happening because we call the write method also for the inactive components
https://github.com/ros-controls/ros2_control/blob/master/hardware_interface%2Fsrc%2Fsystem.cpp#L247 and https://github.com/ros-controls/ros2_control/blob/master/hardware_interface%2Fsrc%2Factuator.cpp#L251

If we need to properly fix it, I think we might need a new method called dynamic_configure where all the gpio interfaces go in and then the main hardware command interfaces can go in the write method, in this way we can call this new dynamic_configure method and avoid calling write method in the inactive state.

Originally posted by @saikishor in ros-controls/ros2_control_demos#455 (comment)

[saikishor]

The above should be fixed by #1451

[christophfroehlich]

The above should be fixed by #1451

I can confirm this by removing the std::is_finite check from example_14: it doesn't fail now any more, but does with reverting 25f2c97

[saikishor]

Thanks a lot for crosschecking @christophfroehlich. You are the best