Moves status icon into a vue file and adds tests

What does this MR do?

1. Moves status icon into a vue file and adds tests (it had done)
2. Moves mr_widget_merging into a vue file
3. Adds i18n
4. Adds better test cases

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• API support added
• Tests added for this feature/bug
• Review
  • Has been reviewed by UX
  • Has been reviewed by Frontend
  • Has been reviewed by Backend
  • Has been reviewed by Database
• Conform by the merge request performance guides
• Conform by the style guides
• Squashed related commits together
• Internationalization required/considered
• End-to-end tests pass (package-qa manual pipeline job)

What are the relevant issue numbers?

#41582 (closed)