### 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)
can_create_dir = false;
			break;
		case FILE_MODE_OPEN_DIR:
			set_ok_button_text(TTR("Open"));
			set_title(TTR("Open a Directory"));
			can_create_dir = true;
			break;
		case FILE_MODE_OPEN_ANY:
			set_ok_button_text(TTR("Open"));
			set_title(TTR("Open a File or Directory"));
			can_create_dir = true;
			break;
		case FILE_MODE_SAVE_FILE:
			set_ok_button_text(TTR("Save"));
			set_title(TTR("Save a File"));
			can_create_dir = true;
			break;
	}
	if (mode == FILE_MODE_OPEN_FILES) {
		item_list->set_select_mode(ItemList::SELECT_MULTI);
	} else {
		item_list->set_select_mode(ItemList::SELECT_SINGLE);
	}
	if (can_create_dir) {
		makedir->show();
	} else {
		makedir->hide();
	}
}
EditorFileDialog::FileMode EditorFileDialog::get_file_mode() const {