feat: expose currencyCode on Product struct in IAP module (#25084)

Co-authored-by: Shur Singh <ssingh@evernote.com>

shell/browser/mac/in_app_purchase_product.h

@@ -28,6 +28,9 @@ struct Product {
   double price = 0.0;
   std::string formattedPrice;
 
+  // Currency Information
+  std::string currencyCode;
+
   // Downloadable Content Information
   bool isDownloadable = false;
 

shell/browser/mac/in_app_purchase_product.mm

@@ -146,6 +146,14 @@
       productStruct.formattedPrice =
           [[self formatPrice:product.price
                    withLocal:product.priceLocale] UTF8String];
+
+      // Currency Information
+      if (@available(macOS 10.12, *)) {
+        if (product.priceLocale.currencyCode != nil) {
+          productStruct.currencyCode =
+              [product.priceLocale.currencyCode UTF8String];
+        }
+      }
     }
   }