Add parsing for nionswift

[mkuehbach]

• [x] Generalized store data for all cases that were observed in Christoph's lab from the Nion data from the last 5 years
• [x] Generalized NXdata for all use cases from the above-mentioned collection
• [x] Generalized mapping table for all metadata from majority of unique concepts from the above-mentioned collection
• [x] Testing with old example dataset
• [x] Update pynxtools/sprint23_em_v3 with latest versions for image and spectrum
• [x] Final testing with metadata mapping