fix(response_cache): change plugin ordering to make sure we can customize caching behavior at the subgraph level

[bnjjj]

With this change you'll now be able to customize cached response using rhai or coprocessors. It's also now possible to set a different private_id based on subgraph request (like headers for example).

Example of rhai script customizing the private_id:

fn subgraph_service(service, subgraph) {
    service.map_request(|request| {
        if "private_id" in request.headers {
            request.context["private_id"] = request.headers["private_id"];
        }
    });
}

---

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[apollo-librarian]

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* graphos/routing/(latest)/performance/caching/response-caching/customization.mdx

Build ID: 21cd86fe8d4cf3fbc3b387d0
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URL: https://www.apollographql.com/docs/deploy-preview/21cd86fe8d4cf3fbc3b387d0

[carodewig]

👍 it's intuitive that caching would be the last layer around a service, allowing you to customize things in how the cached item is determined.
I think it would be worth calling out this behavior in the response caching docs.

Would like another person to review, but this makes sense to me!