remove feature of overriding syntax and syntax_version in parser

[nerdoc]

ATM you can specify the syntax_version (1-4) and the syntax (UNOA, UNOB etc) for the parser. That does not really make sense, as the syntax and version are defined in the UNB header, and it will never make sense that the parser uses another version to parse the EDI file.

So I think it is is ok to remove the possibility of specifying these at the parser creation, this just creates problems that unnecessarily complicate the code.

Unless anyone has a good pattern where these overriding makes sense, I'll remove it. @sabas, @theangryangel, @JocelynDelalande, @hf-kklein - any input? Just a 👍 👎 would suffice - so I can start it