Add WebpushFcmOptions to WebpushConfig (#373)

https://firebase.google.com/docs/reference/fcm/rest/v1/projects.messages#webpushconfig

Author: mmermerkaya

src/index.d.ts

@@ -444,8 +444,13 @@ declare namespace admin.messaging {
     headers?: {[key: string]: string};
     data?: {[key: string]: string};
     notification?: WebpushNotification;
+    fcmOptions?: WebpushFcmOptions;
   };
 
+  interface WebpushFcmOptions {
+    link?: string;
+  }
+
   interface WebpushNotification {
     title?: string;
     actions?: Array<{

src/messaging/messaging.ts

@@ -127,6 +127,11 @@ export interface WebpushConfig {
   headers?: {[key: string]: string};
   data?: {[key: string]: string};
   notification?: WebpushNotification;
+  fcmOptions?: WebpushFcmOptions;
+}
+
+export interface WebpushFcmOptions {
+  link?: string;
 }
 
 export interface WebpushNotification {

test/unit/messaging/messaging.spec.ts

@@ -2220,6 +2220,9 @@ describe('Messaging', () => {
               image: 'test.image',
               requireInteraction: true,
             },
+            fcmOptions: {
+              link: 'https://example.com',
+            },
           },
         },
       },