Handle joint position limits in controlboard

[xela-95]

Joint limits have to managed into the control board plugin.
They are specified both on the model description SDF/URDF (<limit> element) and in the LIMITS group of the controlboard yarp configuration file.

Adequate conversion should take place:

• Quantities coming from Gazebo are in radians (for revolute joints)
• Quantities in yarp configuration files are in degrees

Usually the limits specified in the yarp configuration file are narrower wrt the ones specified from the model description, since the former act as software limits, while the latter as hardware ones.

Moreover, at the current state the Joint API from gz-sim does not provide a method to get joint limits, just to set them.