[base estimator] export full velocity state for v_kin v_imu v_flex and v_gyr so that it is plugable as v

[torque-ctrl] Add output signal for torque error integral, add command to reset error integral, remove useless signals and commands

[current-ctrl] Create new entity CurrentController (the current control was previously implemented inside the ControlManager)

[python] Adapt function to compute torque estimations from sensor data to new API of ForceTorqueEstimator