feat(in-app-purchase-2): update validator for custom headers (#4262)

Author: mariusbackes

src/@awesome-cordova-plugins/plugins/in-app-purchase-2/index.ts

@@ -745,7 +745,13 @@ export class InAppPurchase2 extends AwesomeCordovaNativePlugin {
   products: IAPProducts;
 
   @CordovaProperty()
-  validator: string | ((url: string | IAPProduct, callback: Function) => void);
+  validator:
+    | string
+    | ((url: string | IAPProduct, callback: Function) => void)
+    | {
+        url: string;
+        headers?: { [token: string]: string };
+      };
 
   @CordovaProperty()
   applicationUsername: string | (() => string);
@@ -915,8 +921,11 @@ export class InAppPurchase2 extends AwesomeCordovaNativePlugin {
   /** Opens the Manage Billing page (AppStore, Play, Microsoft, ...), where the user can update his/her payment methods. */
   @Cordova({ sync: true })
   manageBilling(): void {}
-  
+
   /** Open the subscription price change notification workflow. (Play) See: https://developer.android.com/google/play/billing/subscriptions#price-change-communicate */
   @Cordova({ sync: true })
-  launchPriceChangeConfirmationFlow(productId: string, callback: (status: 'OK' | 'UnknownProduct' | 'UserCanceled') => void): void {};
+  launchPriceChangeConfirmationFlow(
+    productId: string,
+    callback: (status: 'OK' | 'UnknownProduct' | 'UserCanceled') => void
+  ): void {}
 }