### 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)
dir_access->change_dir(p_dir);
	invalidate();
	update_dir();
	_push_history();
}
void EditorFileDialog::_file_submitted(const String &p_file) {
	_action_pressed();
}
void EditorFileDialog::_save_confirm_pressed() {
	String f = dir_access->get_current_dir().path_join(file->get_text());
	_save_to_recent();
	hide();
	emit_signal(SNAME("file_selected"), f);
}
void EditorFileDialog::_post_popup() {