### 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)
#include "editor_file_dialog.h"
#include "core/config/project_settings.h"
#include "core/io/file_access.h"
#include "core/os/keyboard.h"
#include "core/os/os.h"
#include "editor/dependency_editor.h"
#include "editor/editor_file_system.h"
#include "editor/editor_node.h"
#include "editor/editor_resource_preview.h"
#include "editor/editor_scale.h"
#include "editor/editor_settings.h"
#include "scene/gui/center_container.h"
#include "scene/gui/label.h"
#include "scene/gui/margin_container.h"
#include "scene/gui/option_button.h"
#include "scene/gui/separator.h"
#include "scene/gui/split_container.h"
#include "scene/gui/texture_rect.h"
#include "servers/display_server.h"
EditorFileDialog::GetIconFunc EditorFileDialog::get_icon_func = nullptr;
EditorFileDialog::GetIconFunc EditorFileDialog::get_thumbnail_func = nullptr;
EditorFileDialog::RegisterFunc EditorFileDialog::register_func = nullptr;
EditorFileDialog::RegisterFunc EditorFileDialog::unregister_func = nullptr;
void EditorFileDialog::popup_file_dialog() {