Refactor search token to prepare EE version

What does this MR do and why?

This change prepares the components and tests for additional EE-only filters.

User searches mock data is exported to a separate file so it can be reused in EE and CE tests respectively.

Why?

#365078 (closed) is a GitLab Ultimate feature.

I have already pushed a Draft: that leverages these changes at !91689 (merged).

Screenshots or screen recordings

NA

How to set up and validate locally

NA

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #365078 (closed)