Move jacob's ladder into metainfo

Store a new quantity called DFT.jacobs_ladder, which usurps the role of DFT.xc_functional_type. The latter should be preserved for the GUI until after reprocessing.

Moreover, the actual value to be stored should match those shown in the GUI, i.e. LDA, GGA, Meta-GGA, Hyper-GGA, Hybrid. In the case of GW.starting_point_type, HF should also be included / preserved.