Fix ddoc params abuse in std.net.curl.HTTP.onProgress.
Fix ddoc params abuse for std.net.curl.FTP.onProgress.

Refactor callback params as macro to minimize copy-n-paste.
Fix ddoc params abuse in std.net.curl.SMTP.onProgress.
Merge pull request #2427 from quickfur/issue11834

Issue 11834: std.net.curl abuses ddoc params section and causes ddoc warnings