### 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)
if (p_mouse_button_index != MouseButton::RIGHT && p_mouse_button_index != MouseButton::LEFT) {
		return;
	}
	
	for (int i = 0; i < item_list->get_item_count(); i++) {
		item_list->deselect(i);
	}
	if (p_mouse_button_index != MouseButton::RIGHT) {
		return;
	}
	item_menu->clear();
	item_menu->reset_size();
	if (can_create_dir) {
		item_menu->add_icon_item(theme_cache.folder, TTR("New Folder..."), ITEM_MENU_NEW_FOLDER, KeyModifierMask::CMD_OR_CTRL | Key::N);
	}
	item_menu->add_icon_item(theme_cache.reload, TTR("Refresh"), ITEM_MENU_REFRESH, Key::F5);
#if !defined(ANDROID_ENABLED) && !defined(WEB_ENABLED)
	
	item_menu->add_separator();
	item_menu->add_icon_item(theme_cache.filesystem, TTR("Open in File Manager"), ITEM_MENU_SHOW_IN_EXPLORER);
#endif
	item_menu->set_position(item_list->get_screen_position() + p_pos);
	item_menu->reset_size();
	item_menu->popup();
}
void EditorFileDialog::_item_menu_id_pressed(int p_option) {