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

[bact]

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:

spec-parser/spec_parser/rdf.py

Lines 276 to 280 in fb5800c

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

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:

spec-parser/spec_parser/rdf.py

Lines 267 to 280 in fb5800c

	for _, _, o in g.triples((subject, RDFS.range, None)):
	if o in vocab_classes:
	return {
	"@id": subject,
	"@type": "@vocab",
	"@context": {
	"@vocab": o + "/",
	},
	}
	elif (o, RDF.type, OWL.Class) in g:
	return {
	"@id": subject,
	"@type": "@vocab",
	}

Ref: spdx/spdx-3-model#1167