pass useEmbedded to mercure manager's data transformer

[PawelSuwinski]

Data provider does not pass useEmbedded setting to mercure manager's data transformer, default value (false) is always used here.

So if there is any embedded field on the list it is cleared (as side effect) by mercure update, ex:

  <NumberField
     label="Price"
     source="cost.price"
     options={{ style: "currency", currency: "EUR" }}
   />

fetched data:

      (...)
      "cost": {
        "@id": "/costs/375384",
        "@type": "https://schema.org/PriceSpecification",
        "price": 10,
        "priceCurrency": "EUR",
       },

But updated record that can't be properly rendered will be:

{
  (...)
  cost: '/costs/375384`,
}

This PR fix this passing useEmbedded prop to mercure dataTransformer.

[dunglas]

Thank you!!