Simplified PyConf DaVinci configuration

Working on the simplification of DaVinci configuration using PyConf. Now run_davinci takes a single list of nodes as input. Still wondering the best user experience when running multiple selections, currently using DVHelper to prepare the nodes. Tupling test file updated to create two tuples from different selections on the same dataset.

Work on DPA task https://gitlab.cern.ch/lhcb-dpa/project/-/issues/48.

Not to be merged before !539 (merged) decided to merge this first Needs !539 (merged).

Needs Analysis!792 (merged) to avoid error from FunTuple.