Add Scalability/FileUploads cop

What does this MR do?

This cop prevents you from using File type parameters in API, it points you to the development documentation about workhorse file acceleration.

Closes gitlab-org/gitlab-ee#14925, follow-up fixes are tracked in gitlab-org/gitlab-ee#14960

Does this MR meet the acceptance criteria?

Conformity

• [-] Changelog entry for user-facing changes, or community contribution. Check the link for other scenarios.
• [-] Documentation created/updated or follow-up review issue created
• Code review guidelines
• [-] Merge request performance guidelines
• Style guides
• [-] Database guides
• Separation of EE specific content