### 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 (mode == FILE_MODE_OPEN_ANY || mode == FILE_MODE_SAVE_FILE) {
		return false;
	}
	Vector<int> items = item_list->get_selected_items();
	if (items.size() == 0) {
		return mode != FILE_MODE_OPEN_DIR; 
	}
	for (int i = 0; i < items.size(); i++) {
		Dictionary d = item_list->get_item_metadata(items.get(i));
		if (((mode == FILE_MODE_OPEN_FILE || mode == FILE_MODE_OPEN_FILES) && d["dir"]) || (mode == FILE_MODE_OPEN_DIR && !d["dir"])) {
			return true;
		}
	}
	return false;
}
void EditorFileDialog::update_file_name() {