[ENH] Convert defacing workflow to PET App on brainlife.io

[bendhouseart]

Franco Pestilli has expressed interest in converting this workflow to a PET BIDS app on brainlife. Convert this current workflow into a brainlife app and test the workflow on data when uploaded to brainlife.

[bendhouseart]

This is most likely going to need be broken into several additional issues per the instructions provided by Franco.