### 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 current = p_item;
	if (current < 0 || current >= item_list->get_item_count()) {
		return;
	}
	Dictionary d = item_list->get_item_metadata(current);
	if (!d["dir"]) {
		file->set_text(d["name"]);
		_request_single_thumbnail(get_current_dir().path_join(get_current_file()));
		
		set_ok_button_text(TTR("Open"));
	} else if (mode == FILE_MODE_OPEN_DIR || mode == FILE_MODE_OPEN_ANY) {
		file->set_text("");
		set_ok_button_text(TTR("Select This Folder"));
	}
	get_ok_button()->set_disabled(_is_open_should_be_disabled());
}
void EditorFileDialog::_multi_selected(int p_item, bool p_selected) {
	int current = p_item;
	if (current < 0 || current >= item_list->get_item_count()) {
		return;
	}
	Dictionary d = item_list->get_item_metadata(current);
	if (!d["dir"] && p_selected) {
		file->set_text(d["name"]);
		_request_single_thumbnail(get_current_dir().path_join(get_current_file()));
	}
	get_ok_button()->set_disabled(_is_open_should_be_disabled());
}
void EditorFileDialog::_items_clear_selection(const Vector2 &p_pos, MouseButton p_mouse_button_index) {