Add partial oxidation (POX) hydrogen production technology

[dobrien13]

POX makes up ~10% of EU's H2 production, and nearly 50% of H2 made on-site at refineries. (https://www.petrochemistry.eu/wp-content/uploads/2021/03/Petrochemicals_Paper_hydrogen-1.pdf)

For now, we assign this share to steam reforming, but most POX uses heavy fuel or residue stream of the refinery, so we are currently mis-representing feedstock use in refining somewhat significantly.

[dobrien13]

In commit #7f56967, I replaced thermochemical water splitting with partial oxidation of hydrocarbons. I simply changed each input file and modified the hydrogen production pathway subscript. For review @mkmahajan if you have a minute!