Fix Android bugs (#941)

* Add an explicit value for the hasFragileUserData parameter

* Fix app crashes when canceling file opening

* Fix requestNetwork bug for Android 11

* Fix activity onStop method

client/android/AndroidManifest.xml

@@ -38,6 +38,7 @@
         android:theme="@style/NoActionBar"
         android:fullBackupContent="@xml/backup_content"
         android:dataExtractionRules="@xml/data_extraction_rules"
+        android:hasFragileUserData="false"
         tools:targetApi="s">
 
         <activity