Setup RDF and schema URL redirections for 3.0

[bact]

Due to spdx/spdx-3-model#1046:

• Setup JSON schema URL redirection: https://spdx.org/schema/3.0/spdx-json-schema.json
• Make it redirected to https://spdx.github.io/spdx-spec/3.0/rdf/schema.json

Note: the @context.const value in the schema file needs to be updated as well.

Currently it is:

        "@context": {
            "const": "https://spdx.org/rdf/3.0.1/spdx-context.jsonld"
        }

Need to change to:

        "@context": {
            "const": "https://spdx.org/rdf/3.0/spdx-context.jsonld"
        }