Harmonization of BECCS and A/R

[coroa]

• CO2|CDR BECCS should use a 0-history harmonization (ie takes model values literally) on global values

• CO2|CDR Afforestation should use global "Forest regrowth" data from GCB (implemented in global_trajectories excel sheet)

• CO2|Aggregate - Agriculture and LUC should use global GCB LUC flux minus "Forest regrowth" (implemented in global_trajectories excel sheet)

• Need to do a comparison to old harmonisation data!