[predictive-back-navigation] enable for the whole app

Summary:

Back-to-home animation is shown when user swipes back from the main activity.

Test Plan:
* [x] go back from the main activity
* [ ] click on search view, go back, search view should collapse
* [ ] go back to from the package info screen to package list screen
* [ ] go back from app settings screen to the package list screen

app/src/main/AndroidManifest.xml

@@ -29,6 +29,7 @@
         android:name=".MainApplication"
         android:allowBackup="true"
         android:banner="@drawable/tv_banner"
+        android:enableOnBackInvokedCallback="true"
         android:icon="@mipmap/ic_launcher"
         android:label="@string/application_name"
         android:networkSecurityConfig="@xml/network_security_config"