feat: data models publishing refactoring

ref #608

This MR updates jargon webhook and publication pipelines to support processing and publication one data model.

• Schemas and instances were removed from data-modes/untp/artefacts
• context.jsonld file is moved to data-models/untp
• version management simplified

this MR is for jargon snapshots and releases processing and publication to the test endpoint

release and publication to production endpoint will be covered in another MR.