For use when the Writer implementation can cannot offer a more efficient
implementation than a basic read/write loop on the file.
pub fn unimplementedSendFile(w: *Writer, file_reader: *File.Reader, limit: Limit) FileError!usize
pub fn unimplementedSendFile(w: *Writer, file_reader: *File.Reader, limit: Limit) FileError!usize {
_ = w;
_ = file_reader;
_ = limit;
return error.Unimplemented;
}