All terms in EMglossary into NXem, NXem v3 candidate

[mkuehbach]

• [ ] Recover (web)protege account
• [x] Test with one term from EMglossary how to connect to concept in NXem and replacing that concept's docstring:
• [x] Check rendering correctly in documentation (docstring, xref)
• [ ] Check resulting representation in NeXusOntology All of the above 1d
• [x] Add all remaining terms from EMglossary 1d
• [x] Add NXcorrector_astig
• [x] Add NXcorrector_cc
• [x] Add description field in NXevent_data_em pointing to information source inside tech partner file 1.5d
• [x] Update documentation NXcorrector_ax, NXmonochromator_em, NXphase_plate_em, NXbiprism_em
• [x] Update NXem to consider possibility for added NXcomponents_em and source, NXidentifier
• [x] New docstring format: definition ideally pointing just to an URI, opt: has_exact_synonym, opt: comment for human
• [ ] Review, deploy 1d

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• [x] Update pynxtools-em template pathes accordingly

[mkuehbach]

Implemented in prepared PR https://github.com/FAIRmat-NFDI/nexus_definitions/pull/250, writing to fairmat is hold back though to avoid that the current pynxtools-em fails, this refactoring on pynxtools-em is next