Before this commit, the `tsh` HTTP requests that had the extra headers
were those that did not use `roundtrip`.
This commit leverages `http.RoundTripper.RoundTrip` to ensure that all
requests have the the extra headers.
* Enable nolintlint linter
* Fix nolint comments in the api package
* Fix RDP client comment
* Address review comment
Co-authored-by: Alan Parra <alan.parra@goteleport.com>
* Allow unused for nolintlint linter
* Remove redundant casting
* Add comment on why allowed unused is enabled
Co-authored-by: Alan Parra <alan.parra@goteleport.com>
Co-authored-by: Alan Parra <alan.parra@goteleport.com>