Add support to flashtext USDA packager codes

[teolemon]

What

• Add support for the USDA packager codes openfoodfacts-server#3704
• The list is available in the XLSX, in the second tab: "Est. 23466", but there are probably variants we'll find on OCRs.

Part of

• 🎯 What can I work on ? #374
• US support

[GabrielBeFr]

I pushed my modifications to solve this problem about a week ago but, after executing the ocr prediction on a dump of ocr results, I realised the amount of false positive was way too high. I will change my REGEX to make the search more precise. I will also put the Automatic processing to False in order to avoid any problem if we were to put this new feature in prod.
@teolemon what do you think of limitating the search of USDA packager codes to US products ? Do you know if non-US product can also have USDA packager codes ?