MultiBar does not honour custom handle on Windows

Hello,

I am using a "/dev/null" like handle when my application is in quiet mode to hide the progress bar.

On unix, `tty::move_cursor_up` returns a string which is output to the handle.
On windows,` tty::move_cursor_up` print to the console and return an empty string whatever the handle is, making my trick to have a quiet mode totally failing.

I do not know if the windows code could be fixed easily. Otherwise what about introducing a quiet mode ?

Look at the Windows-specific code in the tty module, likely in src/tty.rs or a similar platform-specific file. The function `move_cursor_up` currently prints directly to the console instead of writing to the provided handle. Compare with the Unix implementation to see how it returns a string for output. Test by running the existing tests or creating a minimal example that uses a custom handle like `io::sink`. The fix should ensure the Windows version respects the handle and returns a string, not perform direct I/O.

索引モデルが issue の本文から書いたものです。