android: add notifications foundation with fcm channels and deep links

android/app/src/main/AndroidManifest.xml

@@ -2,6 +2,7 @@
 <manifest xmlns:android="http://schemas.android.com/apk/res/android">
 
     <uses-permission android:name="android.permission.INTERNET" />
+    <uses-permission android:name="android.permission.POST_NOTIFICATIONS" />
 
     <application
         android:name=".MessengerApplication"
@@ -29,6 +30,13 @@
                     android:scheme="https" />
             </intent-filter>
         </activity>
+        <service
+            android:name=".push.MessengerFirebaseMessagingService"
+            android:exported="false">
+            <intent-filter>
+                <action android:name="com.google.firebase.MESSAGING_EVENT" />
+            </intent-filter>
+        </service>
     </application>
 
 </manifest>