Translate JSON parsing errors

[nsoblath]

Should be fixed here:

• scarab/library/param/codec/json/param_json.cc

  Line 73 in 8917efc

  '\t' << t_config_doc.GetParseError() << '\n' <<

• scarab/library/param/codec/json/param_json.cc

  Line 79 in 8917efc

  '\t' << t_config_doc.GetParseError() <<

• scarab/library/param/codec/json/param_json.cc

  Line 95 in 8917efc

  LERROR( dlog, "error parsing string:\n" << t_config_doc.GetParseError() );

Translation as in the end of this section: https://rapidjson.org/md_doc_dom.html#ParseError