Duplicate file or folder on the server

[robinrodricks]

We don't currently support copying a file or folder from the server to another path on the same server.

1. Upload/Download methods are the only way to do this but it creates an unwanted copy on disk.
2. Rename/Move methods don't create a copy.
3. TransferFile and TransferDirectory are when you want to transfer from one server to another.

Proposed fix:

New API required - DuplicateFile and DuplicateDirectory which will create a copy of a file or folder from one path to another path on the same server