chore: migrate from jest to mocha

[43081j]

Migrates from jest to mocha, c8 and tinyspy.

[coveralls]

coverage: 71.18% (-28.2%) from 99.34% when pulling 44b3a6b1d97bfb2e933f305d80a860c34021a0aa on chopchop-mocha into 57a192a03501395ce10759c4f2c1be22a61b0b32 on master.

[43081j]

The coverage drop suggests we missed some test files. I'll take a look 👍

Also this depends on #1267 to avoid having to do the lint config twice

[43081j]

the exact same number of tests run but the coverage is way down on the tokenizer, so I'm taking a look into that

super strange since the coverage is clearly setup to find the right files, it just calculates a much lower value

maybe jest was lying 🤔

[43081j]

giving up on this for #1376 instead which has working coverage