awaitRestoreResult
Restores purchases made with the current Store account for the current user. This method will post all purchases associated with the current Store account to RevenueCat and become associated with the current Purchases.appUserID. If the receipt token is being used by an existing user, the current Purchases.appUserID will be aliased together with the Purchases.appUserID of the existing user. Going forward, either Purchases.appUserID will be able to reference the same user.
You shouldn't use this method if you have your own account system. In that case "restoration" is provided by your app passing the same Purchases.appUserID used to purchase originally.
Return
A Result containing CustomerInfo if successful, and PurchasesException in case of a failure.