Improve encoding support in CSV converter

[tagliala]

Fix #2191

⚠️ Merge with extreme care ⚠️

[bbenezech]

Thanks for this.

@tagliala Can I ask you why you need this?
It used to be back in the days some databases where not in utf-8, especially in asia, but I am wondering if it is needed at all today. What are you thoughts on this?

@mshibuya What should we do? utf8 all the things and stop this madness?

[tagliala]

I run into the issue at #2191, there was a non-utf8 database whose tables could not be exported

Btw you could also drop the whole thing

[bbenezech]

Ok, I read #2191, it seems a lot of people have this issue.
The code looks nice, let's merge this!

Thanks a lot @tagliala