chore: defaultly save files on Android

- defaultly save files on Android instead of share
- add dedicated share button for files and images on Android
- use ListTile instead of row to display file event
- update file_picker_cross

Signed-off-by: TheOneWithTheBraid <the-one@with-the-braid.cf>

lib/pages/image_viewer/image_viewer.dart

@@ -28,6 +28,9 @@ class ImageViewerController extends State<ImageViewer> {
   /// Save this file with a system call.
   void saveFileAction() => widget.event.saveFile(context);
 
+  /// Save this file with a system call.
+  void shareFileAction() => widget.event.shareFile(context);
+
   static const maxScaleFactor = 1.5;
 
   /// Go back if user swiped it away