### Godot version

4.1.3

### System information

Linux

### Issue description

I'm trying to make an editor plugin on Rust:

```rust
#[derive(GodotClass)]
#[class(tool, editor_plugin, init, base=EditorPlugin)]
pub struct MyEditorPluginBase {}
```

But due to some limitations, I still have to use GDScript for some specific things.

So I tried to make a subclass of this Rust class:

```gdscript
@tool
class_name MyEditorPlugin
extends MyEditorPluginBase
```

This would work if `MyEditorPluginBase` was a GDScript class, but since it's a GDExtension class in my case, it doesn't work:

> Unable to load addon script from path: 'res://addons/my_addon/my_editor_plugin.gd' Base type is not EditorPlugin.

But it obviously **IS** EditorPlugin!

![godot-editorplugin-docs](https://github.com/godotengine/godot/assets/3236464/4665deeb-30f0-45cd-bfff-56101b9d4875)

![godot-editorplugin](https://github.com/godotengine/godot/assets/3236464/b1b6ecb4-de22-4abd-91a3-e180691f67ee)

If I understand correctly, this behavior is caused by this function, which checks some mysterious "instance base type" instead of real inheritance:

https://github.com/godotengine/godot/blob/fa4a65387ea41506ecc519fc61a06da110dce51c/editor/editor_node.cpp#L3456-L3458

https://github.com/godotengine/godot/blob/fa4a65387ea41506ecc519fc61a06da110dce51c/modules/gdscript/gdscript.cpp#L260-L263

Since the [documentation](https://docs.godotengine.org/en/stable/tutorials/plugins/editor/making_plugins.html#the-script-file) doesn't say that the script must be a **direct** subclass of EditorPlugin (and an indirect subclass works fine in GDScript), I interpret this behavior as a Godot bug.

### Steps to reproduce

See above

### Minimal reproduction project

[gdext_editor_plugin_test.zip](https://github.com/godotengine/godot/files/13451014/gdext_editor_plugin_test.zip)
editor = false;
#else
		const String error_msg = "Error: Couldn't load project data at path \"" + project_path + "\". Is the .pck file missing?\nIf you've renamed the executable, the associated .pck file should also be renamed to match the executable's name (without the extension).\n";
		OS::get_singleton()->print("%s", error_msg.utf8().get_data());
		OS::get_singleton()->alert(error_msg);
		goto error;
#endif
	}
	
	{
		int worker_threads = GLOBAL_GET("threading/worker_pool/max_threads");
		bool low_priority_use_system_threads = GLOBAL_GET("threading/worker_pool/use_system_threads_for_low_priority_tasks");
		float low_property_ratio = GLOBAL_GET("threading/worker_pool/low_priority_thread_ratio");
		if (editor || project_manager) {
			WorkerThreadPool::get_singleton()->init();
		} else {
			WorkerThreadPool::get_singleton()->init(worker_threads, low_priority_use_system_threads, low_property_ratio);
		}
	}
#ifdef TOOLS_ENABLED
	if (editor) {
		Engine::get_singleton()->set_editor_hint(true);
		Engine::get_singleton()->set_extension_reloading_enabled(true);
	}
#endif
	
	OS::get_singleton()->ensure_user_data_dir();
	initialize_modules(MODULE_INITIALIZATION_LEVEL_CORE);
	register_core_extensions(); 
	ResourceUID::get_singleton()->load_from_cache();