Remove dependency on EXTERNAL_STORAGE permission

Author: bauerj

android/app/src/main/AndroidManifest.xml

@@ -5,6 +5,7 @@
 
     <uses-permission android:name="android.permission.REQUEST_INSTALL_PACKAGES" tools:node="remove"/>
     <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" tools:node="remove"/>
+    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" tools:node="remove"/>
     <!-- io.flutter.app.FlutterApplication is an android.app.Application that
          calls FlutterMain.startInitialization(this); in its onCreate method.
          In most cases you can leave this as-is, but you if you want to provide