IMU test - Fix forward kinematics computation

[martinaxgloria]

During the demo shown at the last PI review, we found an error when asking for the test to be performed on all sensors, while passing a specific list of sensors (i.e. l_arm_ft_imu, r_arm_ft_imu, head_imu_0) resulted in a positive test result for the imu sensor on the head. Trying to combine the elements of this list in different ways, the only green light was obtained when the head_imu_0 was the third element of the list.

Thanks to the precious help of @Nicogene, we found out that it was a leftover in the computation of the forward kinematics. When the test was executed sequentially over the available sensors, the rotation matrix I_R_I_IMU was computed and then overwritten. When the test was refactored to be executed on all the available sensors at the same time, I didn't transform this iDynTree::Rotation in a std::vector<iDynTree::Rotation> (one per sensor).

This PR adds this fix (tested on iCubGenova11 with @Nicogene). Moreover, I also added a new configuration file to be used with robots that are not equipped with legs

[Nicogene]

cc @pattacini