Source field should be different for two different cards by the same provider

[mukundvarma]

Right now, source appears as amex for both Amex Platinum and Amex Blue Cash. It would be better if these two appeared separately

[velicanu]

That's a good point 🤔

One approach we could take is to keep track of the original filename for each record, in addition to the current source.

So the extractor would output something like this:

{
  ...,
  "source_file": "amex-filename.csv"
}

And source file would be preserved to the end.

[velicanu]

Closed by #21