Port tests from undici-fetch

[Ethan-Arrowood]

Porting tests from https://github.com/ethan-arrowood/undici-fetch

[Ethan-Arrowood]

going to let #928 land first before doing this since it includes some changes to the fetch api

[ronag]

@Ethan-Arrowood ping, it has landed