forceTorqueSensors does not export the frame also if exportFrameInURDF is set to true

[Nicogene]

As per title, probably this is intended see:

simmechanics-to-urdf/simmechanics_to_urdf/firstgen.py

Lines 434 to 438 in 4de30eb

	# Augment the exported frames with sensors for which the exportFrameInURDF option is enabled
	# for ftSens in self.forceTorqueSensors:
	# if( ftSens["exportFrameInURDF"] ):
	# exported_frame = {}
	# exported_frame["frameName"]

cc @traversaro