Context file: Set @type to @id for terms that refer to a class

In the context file, use @id as the @type for any term where the range is a class.

For example, for createBy, which its range is Agent class, its entry in context file should look like this:

    "createdBy": {
      "@id": "https://spdx.org/rdf/3.1/terms/Core/createdBy",
      "@type": "@id"
    },

Currently we set the type as @vocab, but Agent is not a vocabulary.

Propose to change these lines:

https://github.com/spdx/spec-parser/blob/fb5800c9e13a805660773886dec3a8c587355951/spec_parser/rdf.py#L276-L280

to:

        elif (o, RDF.type, OWL.Class) in g:
            return {
                "@id": subject,
                "@type": "@id",
            }

o here is not a vocabulary, because line 268, and it is a class, because line 276:

https://github.com/spdx/spec-parser/blob/fb5800c9e13a805660773886dec3a8c587355951/spec_parser/rdf.py#L267-L280

Ref: https://github.com/spdx/spdx-3-model/issues/1167

Start in spec_parser/rdf.py around lines 267-280 and inspect how context entries are generated for ranges that are vocabulary terms versus OWL classes. Update the class-handling branch so class ranges produce the proposed @id type, then verify that generated context entries such as createdBy use @type set to @id.