### Godot version

4.2.dev4

### System information

macOS 13.5.1

### Issue description

The recent addition of an option in iOS export templates to "Export project only" is a welcome addition, since I've always had to set up some final things in XCode anyway for the builds to work. 

![Screenshot 2023-09-06 at 10 35 58](https://github.com/godotengine/godot/assets/17763524/672816ec-253a-4c66-a256-f2b627d7f857)

However, a small issue is that even when it's enabled the export Save dialogue lists the file extension as .ipa as if it's still going to export an app archive and not just the xcode project as expected. 

### Steps to reproduce

- Create an iOS export template.
- Enable the "Export project only" option
- Click "Export project..."
- Observe that the export save dialogue still lists the format as ipa.

![Screenshot 2023-09-06 at 10 40 57](https://github.com/godotengine/godot/assets/17763524/fb6c4e25-ecfc-4619-a04b-504a743d1d9b)


### Minimal reproduction project

Not project related, general export UI.
GDCLASS(EditorExportPlatformIOS, EditorExportPlatform);
	Ref<ImageTexture> logo;
	Ref<ImageTexture> run_icon;
	
	mutable SafeFlag plugins_changed;
	SafeFlag devices_changed;
	struct Device {
		String id;
		String name;
		bool simulator = false;
		bool wifi = false;
	};
	Vector<Device> devices;
	Mutex device_lock;
	Mutex plugins_lock;
	mutable Vector<PluginConfigIOS> plugins;
#ifdef MACOS_ENABLED
	Thread check_for_changes_thread;
	SafeFlag quit_request;
	static void _check_for_changes_poll_thread(void *ud);
#endif
	typedef Error (*FileHandler)(String p_file, void *p_userdata);
	static Error _walk_dir_recursive(Ref<DirAccess> &p_da, FileHandler p_handler, void *p_userdata);
	static Error _codesign(String p_file, void *p_userdata);
	void _blend_and_rotate(Ref<Image> &p_dst, Ref<Image> &p_src, bool p_rot);
	struct IOSConfigData {