modelType should not alias @type in context

[VladimirAlexiev]

cc @mristin

In https://github.com/VladimirAlexiev/aas-core-codegen/tree/main/test_data/jsonld_context/trials#serialization-ttl-jsonld I described how modelType should not alias @type, but have a more "modest" definition.

@ethieblin in admin-shell-io/aas-specs#386 (comment) expressed doubts:

Having one of either of the following solutions should in theory give the same result. In practice, it may fall into an undefined behaviour of the JSON-LD framing libraries.

I still think the aliasing must be removed. @ethieblin can you elaborate the framing problem that you describe with an example?

[mristin]

I'm closing the issue due to inactivity -- I don't think we are going to work on this feature in the near or mid-term. The specification for RDF+SHACL is in progress of substantial improvement (e.g., see: admin-shell-io/aas-specs#421), so once the changes are fleshed out, we can re-consider and re-open this issue.