Fix notification on API level 19 (#4842)

Author: lfkellogg

firebase-appdistribution/src/main/java/com/google/firebase/appdistribution/impl/FirebaseAppDistributionNotificationsManager.java

@@ -195,7 +195,7 @@ private Notification buildFeedbackNotification(
     PackageManager packageManager = context.getPackageManager();
     CharSequence appLabel = packageManager.getApplicationLabel(applicationInfo);
     return new NotificationCompat.Builder(context, FEEDBACK.channelId)
-        .setSmallIcon(R.drawable.ic_baseline_rate_review_24)
+        .setSmallIcon(R.drawable.ic_rate_review)
         .setContentTitle(context.getString(R.string.feedback_notification_title))
         .setContentText(context.getString(R.string.feedback_notification_text, appLabel))
         .setPriority(interruptionLevel.notificationPriority)

firebase-appdistribution/src/main/res/drawable-anydpi-v24/ic_rate_review.xml

@@ -0,0 +1,15 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="24dp"
+    android:height="24dp"
+    android:viewportWidth="24"
+    android:viewportHeight="24"
+    android:tint="#FFFFFF">
+  <group android:scaleX="0.92"
+      android:scaleY="0.92"
+      android:translateX="0.96"
+      android:translateY="0.96">
+    <path
+        android:fillColor="@android:color/white"
+        android:pathData="M20,2L4,2c-1.1,0 -1.99,0.9 -1.99,2L2,22l4,-4h14c1.1,0 2,-0.9 2,-2L22,4c0,-1.1 -0.9,-2 -2,-2zM6,14v-2.47l6.88,-6.88c0.2,-0.2 0.51,-0.2 0.71,0l1.77,1.77c0.2,0.2 0.2,0.51 0,0.71L8.47,14L6,14zM18,14h-7.5l2,-2L18,12v2z"/>
+  </group>
+</vector>