[Humble] Restarting the exercise automatically plays the code, while the play/pause button doesn't update

[pawanw17]

The play button is stuck if I press it again the the code will start from scratch

Should the code execution be stopped when restart is pressed?

This also leads to the widget not starting up when the exercise is restarted

[jmplaza]

Hopefully this issue will be solved with the upcoming RAM and exercise template refactoring. In the new RAM the execution management (play, pause, resume...) is done from the RAM mainly using Linux signals, instead of from the exercise template. And the reset has been reimplemented in a more solid way too.

Current pause only pauses the Gazebo simulator, not the robot application.

[pawanw17]

Fixed with #2451