Modify FlatEx PDF-Importer to support new transaction

[Nirus2000]

https://forum.portfolio-performance.info/t/pdf-import-von-flatex/1752/318

[Nirus2000]

Hello @buchen
Please take a look at this change.

Specifically, it concerns the issue that if no exchange rate is available but one is required (see FlatExDegiroDividende13.txt), taxes are not included in the calculation, for example. I have adjusted lines 3597 to 3611, for example.
However, I'm not really happy with this. It would be better if we could address this issue for both taxes and fees and implement this in ExtractUtils.java (287 - 307). However, I'm missing the ParsedData v, which can set FAILURE.
Upon further consideration, the question of how to handle the .wrap() method and isFailure() via wrap((t, ctx) arises.

The goal would be to implement this point for all importers.

Regards
Alex