extract create_download_response API helper

and put it into a new "api2::helpers" module.

Signed-off-by: Stefan Reiter <s.reiter@proxmox.com>

src/api2.rs

@@ -9,6 +9,7 @@ pub mod status;
 pub mod types;
 pub mod version;
 pub mod pull;
+mod helpers;
 
 use proxmox::api::router::SubdirMap;
 use proxmox::api::Router;