This implementation creates a temporary file (suffixed with .tmp) and
renames it to the expected file name when the file is closed.
If the renaming fails, the destination file is removed and renaming is
tried again to handle cases where renaming over an existing file is not
supported by the underlying OS.
When creating an atomic write stream, the file is only created once it
is closed.
This can be done using a temporary file.
This commit only adds the API but not the proper implementation.
