tempfile-istream

This is a read/write implementation of the windows crate's Windows::Win32::System::Com::IStream interface backed by a temp file on disk. The temp file is created with the tempfile crate, so it will be deleted by the OS as soon as the std::fs::File is closed.

It is intended as an alternative to SHCreateMemStream or CreateStreamOnHGlobal, both of which will hold the entire stream in memory.