fix: Types for extended loaders

[imp-dance]

• Extended loaders now have correct types

Previously, if you extended a loader without providing a transform function, the extended loader would incorrectly inherit the return type from the original loader, instead of the extended queries. Using transform in either one also messed with the types which resulted in having to do the following workaround:

const loaderA = createLoader({
   queries: () => [useGetPokemon()],
});

const loaderB = loaderA.extend({
   queries: () => [useGetUser()],
   transform: (q) => q, // this line is no longer needed to get correct types
})

This should make using a baseLoader with common loading/error-handling throughout your application a bit less cumbersome to work with.