NXmpes arpes import

[rettigl]

Required changes to make the nexus loader for pyarpes work with NXmpes_arpes subdefinition files and to allow conversion into momentum space

[domna]

Do you have an example file you can provide for testing this? If possible we could also add a test for loading the file here.

[rettigl]

Do you have an example file you can provide for testing this? If possible we could also add a test for loading the file here.

There is an example notebook now in https://github.com/FAIRmat-NFDI/pynxtools/tree/dev_nxmpes_arpes/examples/mpes
I still need to upload the corresponding data file somewhere.

[domna]

I did some additional checks and simplification and ruff formatted the nexus endstation. This is good to go now form my side @rettigl. Testing and linting will then be fixed in #2.

[rettigl]

LGTM. Let's add further checks etc. in other PRs.
(I cannot approve as I started this PR)