Make a schema for HcalNanoAOD

[DryRun]

The NanoAOD schema from coffea works OK for HcalNanoAOD, but throws a lot of warnings:

warnings.warn(
/afs/cern.ch/user/d/dryu/HCAL/test/hcalanalysis/venv/lib/python3.8/site-packages/coffea/nanoevents/schemas/nanoaod.py:193: RuntimeWarning: Missing cross-reference index for Electron_jetIdx => Jet
warnings.warn(
/afs/cern.ch/user/d/dryu/HCAL/test/hcalanalysis/venv/lib/python3.8/site-packages/coffea/nanoevents/schemas/nanoaod.py:193: RuntimeWarning: Missing cross-reference index for Electron_photonIdx => Photon
warnings.warn(
/afs/cern.ch/user/d/dryu/HCAL/test/hcalanalysis/venv/lib/python3.8/site-packages/coffea/nanoevents/schemas/nanoaod.py:193: RuntimeWarning: Missing cross-reference index for FatJet_subJetIdx1 => SubJet
...                    

The source is clear, HcalNano doesn't contain any physics objects. We should make an HcalNano-specific schema that doesn't try to load these objects. Further, the schema could handle common operations like repacking the branches split by TS (e.g. DigiHB_adc0/1/2/3/4/5/6/7) into a single object, subtracting the pedestal, etc.