Standardized concept set based on TAB definition

[azimov]

Currently exported concept sets imported into atlas cohorts work but produce annoying javascript alert errors. This seems to be because ATLAS expects fields to be there (concept names, standard fields etc). The export from circepy should aim to be always compatible with this even if the text fields are unknown/not filled in. This may be challenging as a lot of fields are potentially unknown (e.g. if the concepts are standard or not)

[azimov]

The goal of this is now to implement the TAB definition:

https://ohdsi.github.io/TAB/Concept-Set-Specification.html

One noted limitation is that the java implementation does not technically support this as there is some disagreement about optional fields. This might require a hack to support