Revert swr config generic

[huozhi]

Changes

revert #1938

After new mutate API is landed, we're able to clear the cache or partially set cache with it, like mutate((key) => filter(key), data). We encourage users to use mutate API instead of manipulate cache provider itself directly.

Origin Problem

Previously users are struggling with typing with cache provider, and trying to call cache.clear(), which might result into inconsistence between cache provider and react state in swr. So we introduce the new mutate API to let users manipulate cache easily. The type generics for useSWRConfig<CacheType> is a bit redudant if you really want to forcedly type a returned cache from context. You can just use as type guard like below:

const cache = useSWRConfig().cache as CustomCache

By default the cache type is Cache<any>

[codesandbox-ci]

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Latest deployment of this branch, based on commit 537b5af:

Sandbox	Source
SWR-Basic	Configuration
SWR-States	Configuration
SWR-Infinite	Configuration
SWR-SSR	Configuration

[shuding]

Sounds good!