search/batch endpoint: reintroduce correlation ID

In the old API, for the footprint-gold-batch endpoint, it was possible to specify a correlation ID with the id parameter for a given batch item, e.g.

[
    {
      "id": "correlation-id-1",
      "size": 200,
      "scope": [
        "Scope_1_BP"
      ],
      "source": "GLORIA",
      "country": "China",
      "activityID": "GLORIA_Furniture_and_other_manufacturing_n.e.c",
      "impactCategory": [
        "Land_use_Annual_crops",
        "Land_use_Permanent_crops"
      ]
    },
    {
      "id": "correlation-id-2",
      "size": 200,
      "scope": [
        "Scope_1_BP"
      ],
      "source": "GLORIA",
      "country": "Sweden",
      "activityID": "GLORIA_Furniture_and_other_manufacturing_n.e.c",
      "impactCategory": [
        "Land_use_Annual_crops",
        "Land_use_Permanent_crops"
      ]
    }
]

In the new /search/batch endpoint, a correlation ID cannot be specified anymore. Instead, the objects are just returned in the same order. We've discussed the importance and best practice of a correlation ID with Jacob at the time when the initial batch endpoint was created. Not having the correlation ID stops us migrating towards the new API.

We are currently in the process of migrating to the new API. Solving this issue swiftly is important for us to not introduce significant additional effort on our side.

Please reintroduce the correlation ID again.