Jacob's ladder: support for ontology annotation

As a first step to supporting our DFT ontology, I would like to store the URI for some Jacob's Ladder (LDA, GGA, Meta-GGA, hybrids, hyper-GGA, Rung 5/RPA-like) as metadata. My long-term view here is that NOMAD should eventually allow for the option to export data in a knowledge graph format, after which a user can locally enhance it with an ontology.

I am building a DFT ontology (which could be readily extendible to ab initio at large), but it hasn't been published yet. Therefore, I cannot guarantee that the IRL for the Jacob's Ladder subclasses will remain fixed. Since we want this feature for showcase purposes, I suggest that we hold off on merging it into develop, or is there a better workaround?

Implementation-wise, I basically have 1 question and 1 request atm:

1. Do we want a general subsection to store all ontology URIs, or should each go to the most corresponding Metainfo subsection?
2. Would it be possible to, in the GUI, only show the last link in the URI, e.g. if we have /host-domain/ab-initio-ontology/F.owl#GGA to automatically show it as GGA?

In particular, I would really appreciate feedback from @himanel1 and @lucamghi