feat: add customizable fetch function to ApiClientOptions

[IKatsuba]

This pull request introduces a new feature to the ApiClient class in src/core/client.ts to allow custom fetch functions. This enables more flexibility in making HTTP requests, especially in different environments like Node.js and Deno.

[KnorpelSenf]

Can you explain a use case for a custom fetch function?

[IKatsuba]

This PR gives a possibility to use native fetch for Node.js environments instead of node-fetch without breaking change

[KnorpelSenf]

That's a great point. I might remove this again for 2.0 when we migrate to native fetch, we'll see. Either way, I'll open an issue about it first.

[KnorpelSenf]

LGTM. Thanks!

[KnorpelSenf]

@IKatsuba consider signing your commits in the future. We usually require this from all contributors, but I made an exception now.

@all-contributors add @IKatsuba for the idea and the code!

[allcontributors]

@KnorpelSenf

I've put up a pull request to add @IKatsuba! 🎉

[BilagoNet]

Most likely after the update i.e. version 1.31.1 cloudflare workers stopped working, I think it was because fetch was added to this ApiClientOptions.

Error log in Cloidflare workers:
TypeError: Illegal invocation: function called with incorrect this reference.

[KnorpelSenf]

@IKatsuba do you have time to fix up your changes?

[IKatsuba]

@IKatsuba do you have time to fix up your changes?

I will research it during the day today

[KnorpelSenf]

@IKatsuba do you have time to fix up your changes?

I will research it during the day today

Epic, thank you!