### 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.
String pkg_name;
		String binary_name;
		String plist_content;
		String architectures;
		String linker_flags;
		String cpp_code;
		String modules_buildfile;
		String modules_fileref;
		String modules_buildphase;
		String modules_buildgrp;
		Vector<String> capabilities;
		bool use_swift_runtime;
	};
	struct ExportArchitecture {
		String name;
		bool is_default = false;
		ExportArchitecture() {}
		ExportArchitecture(String p_name, bool p_is_default) {
			name = p_name;
			is_default = p_is_default;
		}
	};
	struct IOSExportAsset {
		String exported_path;
		bool is_framework = false; 
		bool should_embed = false;
	};
	String _get_additional_plist_content();
	String _get_linker_flags();
	String _get_cpp_code();