Implement scripts to fetch and preprocess raw Unihan data

[Transfusion]

Processing Unihan data (Unihan_IRGSources.txt, Unihan_Readings.txt, and Unihan_Variants.txt) into the ReverseMap, VariantRadicals, and BaseRadicals in the browser already takes more than 10 seconds, which will only get worse with the upcoming implementation of the "find all islands" algorithm and addition of Ext. G characters

[Transfusion]

https://spectrum.chat/create-react-app/general/how-can-tests-outside-of-src-be-included-in-the-test-run~3610ecf1-a396-466b-8f62-a62627062151

I'm working on a project that has helper build scripts to autogenerate certain files within the application

So, this is a case where you'd definitely want to have your own Jest config IMO - because our config is specifically designed to compile code in the same way that CRA does, whereas your scripts won't (I'm guessing) be using our Babel config, etc...