Clear and concise description of the problem

Currently there is no convention defining where test reporters should place files on file system. For example in Playwright there is test-results.

This becomes tricky on third party reporters, as they need to instruct users to update their .gitignore with their own directory.

Suggested solution

Decide what directory reporters should use by default. Document this in Vitest reporter documentation.

Instruct that reporters should never remove this directory. Instead they should add their own directory there, and clear that during re-runs.

If any built-in reporters would use this by default, introduce that in Vitest 5 as breaking change.

Alternative

Wait longer and see how badly the ecosystem around test reporters drifts.

Additional context

Validations

• Follow our Code of Conduct
• Read the Contributing Guidelines.
• Read the docs.
• Check that there isn't already an issue that requests the same feature to avoid creating a duplicate.