Add possibility to add empty list of actuated joints

[Giulero]

With this PR I want to add the possibility of not passing a list of actuated joints to the model constructor.
In this case, all the joints that are not fixed are considered actuated joints, e.g.

from adam.casadi import KinDynComputations
... 
comp = KinDynComputations(model_path)
...

I also added a check that verifies if all the joints passed as an argument of KinDynComputations are in the robot.

[GiulioRomualdi]

Nice! Green flag!

[Giulero]

Thanks @GiulioRomualdi !