chore: UX Feedback when selecting files needs some time

lib/utils/file_selector.dart

@@ -1,3 +1,4 @@
+import 'package:fluffychat/widgets/future_loading_dialog.dart';
 import 'package:flutter/widgets.dart';
 
 import 'package:file_picker/file_picker.dart';
@@ -14,14 +15,17 @@ Future<List<XFile>> selectFiles(
 }) async {
   if (!PlatformInfos.isLinux) {
     final result = await AppLock.of(context).pauseWhile(
-      FilePicker.platform.pickFiles(
+      showFutureLoadingDialog(
+        context: context,
+        future: () => FilePicker.platform.pickFiles(
           compressionQuality: 0,
           allowMultiple: allowMultiple,
           type: type.filePickerType,
           allowedExtensions: type.extensions,
         ),
+      ),
     );
-    return result?.xFiles ?? [];
+    return result.result?.xFiles ?? [];
   }
 
   if (allowMultiple) {