Fix types and units for inherited fields in MPES

[lukaspie]

When starting to build sibling inheritance in the NexusTree of pynxtools, I found these small inconsistencies where fields in MPES-related appdefs had mismatches to the same fields defined in base classes or in the MPES application definition.

Summary by Sourcery

Fix field type and unit inconsistencies in MPES and XPS NeXus definitions

Bug Fixes:

• Correct field types from NX_NUMBER to NX_FLOAT for distance fields
• Add missing type specifications for numeric fields in XPS fit parameters

Enhancements:

• Standardize field types for various measurements in MPES and XPS definitions
• Add missing units to setpoint and other fields in MPES and XPS definitions

[lukaspie]

Here's the draft for inheritance of fields and attributes that led to these inconsistencies being detected: FAIRmat-NFDI/pynxtools#621

[rettigl]

Changes make sense to me.
Generally, with our current implementation I see restriction to NX_FLOAT at various places a bit problematic, if one does not have influence on the data type of some fields, i.e. would have to change the reader for that. So I am wondering if it would not make sense to introduce silten int to float conversion for NX_FLOAT.