Task: Deprecate old serverlessworkflow package

[lornakelly]

Description

Deprecate the old serverlessworkflow package in favour of @openworkflowspec/diagram-editor package

Motivation

Name, github org and npm org have all changed from Serverless Workflow Specification to Open Workflow Specification and the diagram editor mvp needs to be released under new name to align with this

Proposed Implementation

No response

Definition of Done

• Implementation: Fully implemented according to the Serverless Workflow spec.
• Unit Tests: Comprehensive unit tests are included and passing.
• Integration Tests: Verified within the monorepo and target environments (Web/VS Code).
• Documentation: Updated README.md, ADRs, or official docs.
• Performance: No significant regression in editor responsiveness.
• Accessibility: UI changes comply with accessibility standards.