fix(class): throw error when class is extending itself

[stefanblaginov]

Closes #750

Changes

Adds validation for cases where a class (an asset, event, concept, participant or transaction) is extending itself. The validations are performed when:

• parse-ing CTO to JSON AST.
• print-ing JSON AST to CTO.
• Loading JSON AST into the model manager.

The following will be caught by the anti-self-extension validation:

concept Self_Extending extends Self_Extending {}

{
  "$class": "concerto.metamodel@1.0.0.ConceptDeclaration",
  "name": "Self_Extending",
  "isAbstract": false,
  "properties": [],
  "superType": {
    "$class": "concerto.metamodel@1.0.0.TypeIdentified",
    "name": "Self_Extending"
  }
}

Author Checklist

• Ensure you provide a DCO sign-off for your commits using the --signoff option of git commit.
• Vital features and changes captured in unit and/or integration tests
• Commits messages follow AP format
• Extend the documentation, if necessary
• Merging to main from fork:branchname