CSV exports lack header row

[xjamesb]

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Summary

CSV exports do not have a header row that contains the column title

Steps to reproduce

1. search for a string for example "formidable id" in posts and pages with no flags and Action = "No action". Count the number of matches (60)
2. change the action to "Export Matches" with the format "CSV"
3. Verify that 60 rows are present but that there is no header row

Environment

All current.