Update useSWR and useSWRInfinite to return same response references if nothing has changed

[rikutiira]

Currently if you call the same useSWR hook twice (e.g. when component re-renders), the returned response is not the same reference as what the previous call returned even though nothing has changed. Using the returned response with hooks such as useEffect, useMemo or useCallback will therefore cause unnecessary computations to happen.

I would like to open a PR to update useSWR and useSWRInfinite to return the same response reference if nothing has changed, which is as simple as wrapping the returned response object in useMemo call.

I temporarily patched SWR for our project but hopefully this could be merged to SWR soon as it's a very quick and small fix.

[rikutiira]

Hey, is it okay to open a PR about this? 😅

[stem-ui]

@rikutiira can you share what you did to patch this?