### 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.
#ifndef IOS_EXPORT_PLUGIN_H
#define IOS_EXPORT_PLUGIN_H
#include "godot_plugin_config.h"
#include "core/config/project_settings.h"
#include "core/io/file_access.h"
#include "core/io/image_loader.h"
#include "core/io/marshalls.h"
#include "core/io/resource_saver.h"
#include "core/io/zip_io.h"
#include "core/os/os.h"
#include "core/templates/safe_refcount.h"
#include "core/version.h"
#include "editor/editor_settings.h"
#include "editor/export/editor_export_platform.h"
#include "main/splash.gen.h"
#include "scene/resources/image_texture.h"
#include <string.h>
#include <sys/stat.h>
const String ENV_IOS_PROFILE_UUID_DEBUG = "GODOT_IOS_PROVISIONING_PROFILE_UUID_DEBUG";
const String ENV_IOS_PROFILE_UUID_RELEASE = "GODOT_IOS_PROVISIONING_PROFILE_UUID_RELEASE";
class EditorExportPlatformIOS : public EditorExportPlatform {