Check orientations of ft sensors in the arms

[Nicogene]

With #22 we added the unit test that checks the ft sensors orientation.
Using the root-ftSensor transformation used for icub3 makes the test fail:

ergocub-model-test : transform between root_link and l_arm_ft_sensor is not the expected one, test failed.
ergocub-model-test : Expected transform : -0.267012 -0.961047 0.0713662
-0.960459 0.271447 0.0619303
-0.0788901 -0.0520081 -0.995526

ergocub-model-test : Actual transform : -0.250563 -0.961047 0.116648
-0.935113 0.271447 0.227771
-0.250563 -0.0520081 -0.966702


ergocub-model-test : base_link test performed correctly 
ergocub-model-test : transform between root_link and r_arm_ft_sensor is not the expected one, test failed.
ergocub-model-test : Expected transform : -0.267012 0.961047 0.0713662
0.960459 0.271447 -0.0619303
-0.0788901 0.0520081 -0.995526

ergocub-model-test : Actual transform : -0.250563 0.961047 0.116648
0.935113 0.271447 -0.227771
-0.250563 0.0520081 -0.966702

If this discrepancy with icub3 is correct, we can ignore this issue and change the expected transformations in the unit tests reading them from the creo

cc @pattacini @traversaro @Mick3Lozzo @salvi-mattia @mfussi66

[Nicogene]

The discrepancy in the orientation is due to the fact that icub3 and ergocub mechanisms are saved with different joints configurations (shoulder_roll), then we can ignore this difference and make the test happy. (see #7 (comment))