### 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)
String d = drives->get_item_text(p_idx);
	dir_access->change_dir(d);
	file->set_text("");
	invalidate();
	update_dir();
	_push_history();
}
void EditorFileDialog::_update_drives(bool p_select) {
	int dc = dir_access->get_drive_count();
	if (dc == 0 || access != ACCESS_FILESYSTEM) {
		drives->hide();
	} else {
		drives->clear();
		Node *dp = drives->get_parent();
		if (dp) {
			dp->remove_child(drives);
		}
		dp = dir_access->drives_are_shortcuts() ? shortcuts_container : drives_container;
		dp->add_child(drives);
		drives->show();
		for (int i = 0; i < dir_access->get_drive_count(); i++) {
			String d = dir_access->get_drive(i);
			drives->add_item(dir_access->get_drive(i));
		}
		if (p_select) {
			drives->select(dir_access->get_current_drive());
		}
	}
}
void EditorFileDialog::_update_icons() {