feat: add support for custom fetch implementation

[steebchen]

Allows passing a custom fetch function via config for HTTP requests.

[good-lly]

Thank you for this PR! Could you please elaborate on the motivation? What issue does this solve, and in which environment?

[steebchen]

It allows for a custom fetch implementation, which might bring various use cases of a custom fetch function, but my specific use case was for https://github.com/cloudflare/workerd internal functions which provides its own fetch function for a specific network instead of the global fetch, so this PR allows me to do that.

[steebchen]

The only thing I'm not sure about is whether the default = globalThis.fetch is correct, maybe = fetch might be a better default

[good-lly]

ok, I can merge it - but can you add some simple e2e test for that feature?

[steebchen]

15557c3 (#45)

[steebchen]

also it seems globalThis is the way to go:

"globalThis" is a standardized, cross-platform, and universal way to access the global object across all JavaScript environments (browsers, Node.js, web workers, etc.). It was introduced in ECMAScript 2020 to unify access to the global object.

[steebchen]

thanks for merging!

[good-lly]

thanks for merging!

thanks for your contribution!!!! Going to doublecheck on weekend and make new release!