add flutterfire plugin

android/app/build.gradle

@@ -1,12 +1,15 @@
 plugins {
     id "com.android.application"
+    // START: FlutterFire Configuration
+    id 'com.google.gms.google-services'
+    // END: FlutterFire Configuration
     id "kotlin-android"
     // The Flutter Gradle Plugin must be applied after the Android and Kotlin Gradle plugins.
     id "dev.flutter.flutter-gradle-plugin"
 }
 
 def keystoreProperties = new Properties()
-def keystorePropertiesFile = rootProject.file('dev-key.properties')
+def keystorePropertiesFile = rootProject.file('key.properties')
 if (keystorePropertiesFile.exists()) {
     keystoreProperties.load(new FileInputStream(keystorePropertiesFile))
 }