feat(csv): add download headers within csv dialect

[wiedld]

Part of https://github.com/influxdata/idpe/issues/16210

Per feedback from the automation team (see this PR https://github.com/influxdata/idpe/pull/16212), and with approval of @nathanielc , making changes to the csv Dialect to add download headers.

Background:

• we are doing direct filesystem download of data in the UI, bypassing browser memory.
• With this approach, the download filename is only configured with content-disposition headers.
• Made changes in queryrouterd to add the headers.
• Per automation team's request, pushing the header change into the csv Dialect.

Checklist

• ✏️ Write a PR description, regardless of triviality, to include the value of this PR
• 🔗 Reference related issues
• 🏃 Test cases are included to exercise the new code --> test cases are in idpe.
  * did not add Headers test to this repo, since I didn't see other headers tested.
  * Did add an idpe test case, which has already been successfully run with local changes in this package. Confirmed works.