Get all variants of an item

{
    "status": "success",
    "message": "Operation completed successfully",
    "data": {
        "variants": [
            {
                "_id": "507f1f77bcf86cd799439011",
                "name": "Delicious Pizza",
                "description": "Fresh pizza with premium ingredients",
                "basePrice": 25.99,
                "optionName": "Size",
                "parentItem": "507f1f77bcf86cd799439010",
                "isVariant": false,
                "prepTime": "15 minutes",
                "discount": {
                    "type": "percentage",
                    "value": 20,
                    "startDate": "2024-01-01T00:00:00.000Z",
                    "endDate": "2024-12-31T23:59:59.999Z",
                    "isActive": true
                },
                "isActive": true,
                "isAvailable": true,
                "isGroupAvailable": true,
                "order": 1,
                "category": "507f1f77bcf86cd799439012",
                "vendor": "507f1f77bcf86cd799439013",
                "imagePath": "/uploads/items/image.jpg",
                "createdAt": "2019-08-24T14:15:22.123Z",
                "updatedAt": "2019-08-24T14:15:22.123Z"
            }
        ]
    }
}