adjustments of archive and schema for latest NXopt definition

This is try Nbr. 2, as !1855 (closed) was messed up in the local rebasing process:

This merged request aims to update the ellipsometry example data to be in line with the overhaul of the NeXus definition for optical spectroscopy and ellipsometry. The structure of the "ellips.archive.json" and "ellips.scheme.archive.yml" was adjusted to match the new NeXus definitions. Changes of the "eln_data.yaml" file, are due to the processing of the new .yml and .json files in the nomad uploads section. Changes of the "SiO2onSi.ellips.nxs" file, are due to the processing via the jupyther notebook "Ellipsometry workflow example.ipynb".

By these adjustments, the jupyther notebook file parsing of the "ellipsometry example" is fixed, as the NXopt/NXellipsometry definitions were updated.