Function forwardTransaction
forwardTransaction(  
      transactionId: string,  
      productId: string,  
      quantity: number,  
  ): Promise<void>
Forwards StoreKit 2 transaction id, product id and quantity for in-app purchases and subscriptions from your iOS app to the justtrack backend. Available starting with iOS 15.
Parameters
| Name | Type | Description | 
|---|---|---|
| transactionId | string | Transaction identifier. | 
| productId | string | Product identifier. | 
| quantity | number | Number of products. | 
Returns
 Promise<void>
A promise which is resolved once the SDK handles the transaction.