### 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 (d["dir"]) {
					path = path.path_join(d["name"]);
					break;
				}
			}
		}
		_save_to_recent();
		hide();
		emit_signal(SNAME("dir_selected"), path);
	}
	if (mode == FILE_MODE_SAVE_FILE) {
		bool valid = false;
		if (filter->get_selected() == filter->get_item_count() - 1) {
			valid = true; 
		} else if (filters.size() > 1 && filter->get_selected() == 0) {
			
			for (int i = 0; i < filters.size(); i++) {
				String flt = filters[i].get_slice(";", 0);
				for (int j = 0; j < flt.get_slice_count(","); j++) {
					String str = flt.get_slice(",", j).strip_edges();
					if (f.match(str)) {
						valid = true;
						break;
					}
				}
				if (valid) {
					break;
				}
			}
		} else {