Retain UTF-8 BOM on Save

[d99kris]

Discussed in #130

^{Originally posted by hkottmann February 11, 2023}
I'm programming with Qt and included rapidcsv as it is the most efficient library to edit *.csv files. According to the documentation, I've defined HAS_CODECVT before I include rapidcsv.h in my program

`#ifndef HAS_CODECVT
#define HAS_CODECVT

#include "smartdcpd.h"
#include "ui_smartdcpd.h"
#include "rapidcsv.h"
`

But the BOM which was set by creating the document will be still removed by rapidcsv