Enforce an object return from `selectFromResult`

[markerikson]

This PR:

• Updates the TS types to ensure that selectFromResult always returns an object, not a primitive
• Fixes deletion of the build folder to work cross-platform
• Fixes up formatting

I'd found a lovely edge case in my own app where I had:

selectFromResult: (res => res?.items?.length ?? 0)

Unfortunately, due to how the result stuff gets merged together later, I ended up with number & BunchOfResultData, which is of course not valid at all. I had to ensure that I returned the value inside an object.

So, now we enforce that at the type level too.

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size-limit report 📦

Path	Size
ESM full	10.15 KB (0%)
ESM full (React)	11.56 KB (0%)
createApi + setupListeners	9.19 KB (0%)
createApi (React) + setupListeners	10.46 KB (0%)
fetchBaseQuery	701 B (0%)
retry	278 B (0%)
ApiProvider	400 B (0%)
CJS minfied	15.67 KB (0%)
CJS React minfied	17.37 KB (0%)