Expose `queryClient` in QueryFunctionContext

[GLabat]

however, composing query functions from other queries of the same client seems useful. for example, you can currently do this via:

const queryClient = useQueryClient()
useQuery(key, () => queryClient.getQueryData(something) ?? axios.get(...))

if the query function is not inlined, passing the client is necessary, so I agree that having the client injected might be useful in some cases. I'll definitely think about it :)

Originally posted by @TkDodo in #2764 (comment)

This issue is a follow-up of the discussion above.
The idea is to have access to the queryClient in the queryFn, using QueryFunctionContext to simplify usage when the queryFn is defined outside of a useQuery/fetchQuery call.

[GLabat]

Should consider #2548 which adds the ability to nest QueryClient contexts.
Once merged, if the queryClient is passed in someway to the queryFn, it should the "good" one, ie. the one from the query context.

[TkDodo]

I've decided to not move along with this for now. The use-case is pretty narrow, and the custom context complicates that a bit more. There also doesn't seem to be an incredible need for this features.

[Tirzono]

I would be interested in having this feature. Is the reason why this is not considered the fact that it is too much work or is it that this functionality is not wanted? If it's the first then I might be able to look into it. What are the things to consider that could make the implementation difficult?

[TkDodo]

you can use the same query from within multiple providers, but there is only one Query instance. Only observers have access to the QueryClient, the query itself (which also runs the queryFn) does not.