### Godot version

4.1.1

### System information

linux

### Issue description

- When favoriting a path in a `FileDialog`, clicking on it travels to `path/to/dir/`.
- When going up a level from there, it doesn't go to `path/to` but to `path/to/dir` (without the `/`).

[simplescreenrecorder-2023-08-18_09.38.37.webm](https://github.com/godotengine/godot/assets/71937306/00c20ad3-292f-4961-84ed-dbc64906df52)

The problem is either (or both) that:
 - loaded path has a trailing `/`
 - parent dir of `stuff/` is considered to be `stuff`

### Steps to reproduce

favorite a directory and use the feature to navigate to it

### Minimal reproduction project

any (i.e. the project manager's "new project" dialog has one)
int idx = filter->get_selected() - 1;
	if ((idx == -1 && filter->get_item_count() == 2) || (filter->get_item_count() > 2 && idx >= 0 && idx < filter->get_item_count() - 2)) {
		if (idx == -1) {
			idx += 1;
		}
		String filter_str = filters[idx];
		String file_str = file->get_text();
		String base_name = file_str.get_basename();
		Vector<String> filter_substr = filter_str.split(";");
		if (filter_substr.size() >= 2) {
			file_str = base_name + "." + filter_substr[0].strip_edges().get_extension().to_lower();
		} else {
			file_str = base_name + "." + filter_str.strip_edges().get_extension().to_lower();
		}
		file->set_text(file_str);
	}
}
void EditorFileDialog::update_file_list() {