[pkg/stanza] csv_parser: Add additional information to the error log message for mismatching field numbers

[Dylan-M]

When debugging code, the error message simply states: wrong number of fields.

The desired additional information consists of the following:

• Expected number fields
• Actual number of fields encountered
• Line number in the file being read

The alternative we used today was to manually count the number of fields by piping the log lines through wc one at a time, or on Windows using the word count feature of Notepad++