Add source streams to ELT sync

{
  "source_streams": [
    {
      "additional_incremental_pointer_ids": [
        "closed_at"
      ],
      "primary_keys": [
        "id"
      ],
      "excluded_substreams": [
        "substream1",
        "substream2"
      ],
      "full_sync_schedule": "0 3 * * 0"
    }
  ]
}

{
  "source_streams": [
    {
      "id": "SCTVdLAcyDTgNx",
      "elt_sync_id": "3LIw2FdxoByya9",
      "name": "users",
      "incremental_primary_key_name": [
        "id"
      ],
      "primary_keys": [
        "id"
      ],
      "excluded_columns": [
        "email"
      ],
      "hashed_columns": [
        "phone"
      ],
      "incremental_pointer_id": "updated_at",
      "additional_incremental_pointer_ids": [
        "closed_at"
      ],
      "created_at": "2020-01-01T00:00:00.000Z",
      "updated_at": "2020-01-01T00:00:00.000Z",
      "excluded_substreams": [
        "substream1",
        "substream2"
      ],
      "sync_interval": "0 0 * * *",
      "full_sync_schedule": "0 3 * * 0"
    }
  ]
}