avoid code duplication between sct_deepseg_lesion and sct_deepseg_sc
avoid code duplication between sct_deepseg_lesion and sct_deepseg_sc


Former-commit-id: a5cc54b065a1e2b08bc52d8efa9b920f2005f767
neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox