This milestone is the umbrella for all efforts to improve HiggsDNA to move towards a more modular version of HiggsDNA that can be overlaid with PocketCoffea (use their helper functions and processor skeletons).

We start on 17th of January after merging !311 (merged).

Note: Efforts focusing on this branch right now: https://gitlab.cern.ch/cms-analysis/general/HiggsDNA/-/tree/pocket-coffea-overlay?ref_type=heads