Add sorting options for /users API

What does this MR do?

Adds order_by and sort params for /users API (admin only)

Are there points in the code the reviewer needs to double check?

no

Why was this MR needed?

So users can be sorted in different order. We already have such functionality for projects.

Screenshots (if relevant)

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?

Closes #42669 (closed). EE MR -> https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/4405