feat: show file path if name missing

Author: danvick

lib/src/form_builder_file_picker.dart

@@ -237,7 +237,7 @@ class _FormBuilderFilePickerState
                       width: double.infinity,
                       color: Colors.white.withOpacity(.8),
                       child: Text(
-                        files[index].name,
+                        '${files[index].name ?? files[index].path}',
                         style: theme.textTheme.caption,
                         maxLines: 2,
                         overflow: TextOverflow.clip,