Toolbar download bug

[MGatner]

Describe the bug
Issuing a DownloadResponse with the DebugToolbar causes a type error when the toolbar attempts to pass total_execution which hasn't been calculated because of the direct Response return.

CodeIgniter 4 version
Latest develop

Affected module(s)
DownloadResponse, DebugToolbar, ToolbarFilter

Expected behavior, and steps to reproduce if appropriate
In a controller with DebugToolbar enabled call return $this->response->download($filename).