UX Audit - Test segment with JSON

### Is your feature request related to a problem? Please describe.

When creating a segment, I type in a value to match and hope it works. I could easily make a mistake like the selector is broader than I thought, or narrower than I thought. This is especially true with regex’s, and with complex selectors with multiple “and” and “or” statements

### Describe the solution you'd like.

Have the ability to test a segment

- API: send segment rules + JSON and return true or false
- Frontend: allow testing with a JSON field

### Describe alternatives you've considered

N/A

### Additional context

_No response_