feat(codegen): Allow query reponse types to be overridden through SanityQueries

[romeovs]

This PR is one of two PR's that implements my feature request (sanity-io/sanity#6934) in sanity-io/sanity, with the help of some pointers from @sgulseth.

The companion PR that implements the code generation for the newly introduced SanityQueries lives at sanity-io/sanity#6997.

It sets up the @sanity/client package to have an interface SanityQueries that @sanity/codegen (or other packages) can hook into assign custom query types automatically based on the queries that are found in the codebase.

This makes it possible to write code that is fully self-typing:

import {defineQuery} from "groq"
import {createClient} from "@sanity/client"

const client = createClient({ /* ...  */ })

// Define a query as a static string
const posts = defineQuery(`*[_type = "post"] { title, tags }`)

// This will automatically be type correctly as PostsResult
const resp = await client.fetch(query)


// The following will be generated by @sanity/codegen
declare module "@sanity/client" {
  type PostsResult = {
    title?: string
    tags?: string[]
  }

  export interface SanityQueries {
    "*[_type = \"post\"] { title, tags }": PostsResult
  }
}

I have tried to set things up so that they are backwards compatible. Users can still manually
pass the types they want to the query, and the type signatures don't change. I have not touched any existing tests and type tests.

For a way to test the type changes, create a file like the above example and ensure all the types line up with what's expected.

There is also a TS Playground that summarizes the changes made by this PR and the companion PR.

[stipsan]

This is awesome 💖 let's ship 🚀