Better TS types

[jdeniau]

Hi,

This PR tries to improve TS typings.

The main changes:

unknown over any

unkown is prefer over any , as any disable type checking. See https://typescript-eslint.io/rules/no-explicit-any/

Promise input and return type

The return type of the promise is the same as the input type, this way, TS can infer the proper return type of this code:

const fetch = (): Promise<SomeType>;

const swrFetch = swrPromise(fetch); // properly infer as `(): Promise<SomeType>

Export type declaration

I exported the main types that could be used in several circumstances, like wrapping swr into another function, or overriding default store (in that case, the Store interface is helpful)

Typing the store

I typed the Store class as the key is an array, and the data is a CacheNode