Adapt fiducial taggers to iso of GenPart

We have two taggers that are commonly used for the definition of the fiducial phase space at particle level:

• https://gitlab.cern.ch/HiggsDNA-project/HiggsDNA/-/blob/master/higgs_dna/workflows/taggers/fiducialClassicalTagger.py?ref_type=heads
• https://gitlab.cern.ch/HiggsDNA-project/HiggsDNA/-/blob/master/higgs_dna/workflows/taggers/fiducialGeometricTagger.py?ref_type=heads

With the potential addition of the iso field to the genPart collection, we should modify these taggers to make use of it.

Proposal:

• Check whether the field iso of genPart collection exists. Based on that, we should have two separate workflows for the fiducial tagging. This retains backward compatibility with older nanoAOD versions where an iso field is not available (then we rely on the current implementation with genIsolatedPhoton)
• Then, the fiducial phase space selection should be implemented. We keep the same one as with GenIsolatedPhoton except that the cut of I_gen < 10 GeV should be implemented (for each of the two photons).