Rework Docxfinder with the new naming schema

[hf-krechan]

The new naming theme of the docx files can simplify the finding of the correct document.

So we need to refactor this part of the code.

[hf-kklein]

relates to #559

[hf-kklein]

you may also like this method:

https://github.com/Hochfrequenz/edi_energy_scraper/blob/ef78a076f81bf15bd622a17fd49974b122f195f9/src/edi_energy_scraper/scraper.py#L117-L140