follow renaming of NXlens_em to NXelectromagnetic_lens

[lukaspie]

In nexusformat/definitions#1423 it was suggested by NIAC to rename NXlens_em to NXelectromagnetic_lens, in accordance with similar names like NXoptical_lens, NXoptical_window, etc.

We need to update the config and test .nxs files to reflect this. Works together with FAIRmat-NFDI/pynxtools#674.

@rettigl do we need to change that elsewhere as well?

[lukaspie]

I had temporarily installed the bring_back_nexus_def branch in pytest.yaml and it worked: https://github.com/FAIRmat-NFDI/pynxtools-mpes/actions/runs/16570512453?pr=55

So we should be good to merge here and then rerun the plugin tests in pynxtools

[coveralls]

Pull Request Test Coverage Report for Build 16570512453

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 81.366%

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Totals
Change from base Build 15823612244:	0.0%
Covered Lines:	131
Relevant Lines:	161

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💛 - Coveralls

[lukaspie]

@rettigl I will merge here so that we can continue working on the pynxtools main. Let me know if there are downstreams tools where a PR is needed to make the same change as here.