Refine NeXus NXmpes format

• replace as standard hdf5 export ("hdf5" --> "nxs")
• is NXmpes-arpes interesting?
• nexus_validate --ignore-undocumented
• configuration file based on pynxtools format?
• from pynxtools.dataconverter.validate_file import validate, validate_cli for test
• look at test in https://github.com/FAIRmat-NFDI/pynxtools/blob/hdf-based-validation/tests/dataconverter/test_validation.py#L2873
• pump-probe https://github.com/FAIRmat-NFDI/pynxtools-mpes/blob/main/tests/data/example.nxs
• Save all data including:
  • Raw data
  • Transformed data
  • 3d cube
  • projection
• Write further metadata to NXCollection
• electron dispersion scan mode --> open enumeration (custom field with custom=True
• Data object (also string) is allowed as axis
• use predefined axes (f.e. E, angle1, angle2)
• NORTH (Normad Remote Tool Hub)