feat: updated schema id to url

[yehjxraymond]

Updated the schema id $id:

• from open-attestation/2.0 to https://schema.openattestation.com/2.0/schema.json
• from open-attestation/3.0 to https://schema.openattestation.com/3.0/schema.json

This will make the schema JSON schema compliant so that online JSON schema validator will not complain about the malformed schema and that we will have a permalink to reference the schema in our documentations as well.

Additionally added the long url as enums to the @type/document to prevent lots of copy-pasted urls in the code.

[john-dot-oa]

:tada: This PR is included in version 3.4.0 :tada:

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

Your semantic-release bot :package::rocket: