performPurchase
Performs an in-app purchase with the given purchase params.
The PaywallPurchaseLogicParams contains the package to purchase along with product change information and the specific subscription option (offer) configured in the paywall.
If a purchase is successful, syncPurchases will automatically be called by RevenueCat.
Return
A PurchaseLogicResult indicating the outcome of the purchase operation.
Parameters
params
The purchase params containing the package, product change information, and offer details.