Add GraphQL mutation to reorder work item

What does this MR do and why?

Add mutation to reorder work item

Changelog: added

References

• #536882 (closed)

Screenshots or screen recordings

Before	After

How to set up and validate locally

MR acceptance checklist

Evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.