the below method has two handlers for the purchase
public func presentPaywallIfNeeded(
fonts: PaywallFontProvider = DefaultPaywallFontProvider(),
shouldDisplay: @escaping @Sendable (CustomerInfo) -> Bool,
purchaseCompleted: PurchaseOrRestoreCompletedHandler? = nil,
restoreCompleted: PurchaseOrRestoreCompletedHandler? = nil
)
How can our application detect when the purchase is completed or restored when using a custom paywall?