refactor(editor): Rewrite TabBar to composition API (no-changelog)

[alexgrozav]

Summary

Migrate TabBar to Composition API and remove unnecessary properties.

Related tickets and issues

https://linear.app/n8n/issue/N8N-7373/rewrite-tabbar-to-composition-api

Review / Merge checklist

• [x] PR title and summary are descriptive. Remember, the title automatically goes into the changelog. Use (no-changelog) otherwise. (conventions)
• [x] Docs updated or follow-up ticket created.
• [x] Tests included.

  A bug is not considered fixed, unless a test is added to prevent it from happening again. A feature is not complete without tests.