Custom fetch support per call

[HugeLetters]

Description

SvelteKit provides a custom fetch function for loaders(which provide data for components) with a bunch of QoL improvements - this fetch functions are specific to each call so they can't be provided on createClient call. Would be nice to have an option to provide custom fetch function per specific openapi-fetch call.

Proposal

Extent FetchOptions type with a fetch parameter akin to ClientOptions - default to createClient specified fetch if not provided.

Checklist

• I’m willing to open a PR for this (see CONTRIBUTING.md)

[drwpow]

I’m open to this, and I think this should be relatively straightforward to implement—maybe just add the same fetch option to FetchOptions as well?