[legacy-framework] allow useQuery to run during SSR or SSG

[jxe]

This allows useQuery to run on the server, iff there's precached data. We do this by calling useReactQuery with enabled:false and seeing if there's data returned. If there's no data, we throw a suspender to emulate the previous behavior.

To prefetch data, you can run something like this in getStaticProps

import { QueryCache } from "react-query"
const cache = new QueryCache()
const queryKey = getQueryKey(queryFn, queryArgs)
await cache.prefetchQuery(queryKey, () => queryFn(queryArgs))

and then you can pass the resulting cache to the client with

import { dehydrate } from "react-query/hydration"
return { props: { queryCache: dehydrate(cache) } }

So you get identical results on first render.

[MrLeebo]

@jxe @flybayer I resolved the merge conflicts and added an exclusion so useQuery doesn't run during SSG when in legacyMode. The failing test passed on my local environment though...

[MrLeebo]

Switched to reactRoot and would you look at that, a green checkmark! It's what I was hoping for, but you can never be sure what you're going to get 😁

[flybayer]

Ok last thing @MrLeebo, do we need to update or add any docs?

[MrLeebo]

@flybayer Definitely. At minimum, the content at https://blitzjs.com/docs/pages#automatic-static-optimization will need to be updated, and there may be other broader repercussions I'm not even aware of yet.