add pch NLO and NNLO theories
Created by: scarlehoff
I never pushed these two... but the fktables are in the server and the grids in https://github.com/NNPDF/theories_slim/pull/35
The report of 4.0 pch against this one: https://vp.nnpdf.science/I4yWhfTHTFy3UPg0gMM_IQ== (the biggest difference is the displaced charm threshold)