Better handling of CsvConverter in inputs

## What?

If a malformed CSV is configured in a data adapter it returns no error in the UI, only in the serverlog there is this very little information:
2025-04-11T20:00:04.330+02:00 ERROR [CsvConverter] Different number of columns in CSV data (1) and configured field names (30). Discarding input.

## Why?

Would like to have better handling of errors:

1. push some alert in the UI that the file is malformed,
2. having a serverlog including the path and filename and maybe also the name of the lookup adapter

Requested in https://github.com/Graylog2/support/issues/219