### 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)
Ref<CanvasItemMaterialConversionPlugin> canvas_item_mat_convert;
		canvas_item_mat_convert.instantiate();
		resource_conversion_plugins.push_back(canvas_item_mat_convert);
		Ref<ParticleProcessMaterialConversionPlugin> particles_mat_convert;
		particles_mat_convert.instantiate();
		resource_conversion_plugins.push_back(particles_mat_convert);
		Ref<ProceduralSkyMaterialConversionPlugin> procedural_sky_mat_convert;
		procedural_sky_mat_convert.instantiate();
		resource_conversion_plugins.push_back(procedural_sky_mat_convert);
		Ref<PanoramaSkyMaterialConversionPlugin> panorama_sky_mat_convert;
		panorama_sky_mat_convert.instantiate();
		resource_conversion_plugins.push_back(panorama_sky_mat_convert);
		Ref<PhysicalSkyMaterialConversionPlugin> physical_sky_mat_convert;
		physical_sky_mat_convert.instantiate();
		resource_conversion_plugins.push_back(physical_sky_mat_convert);
		Ref<FogMaterialConversionPlugin> fog_mat_convert;
		fog_mat_convert.instantiate();
		resource_conversion_plugins.push_back(fog_mat_convert);
		Ref<VisualShaderConversionPlugin> vshader_convert;
		vshader_convert.instantiate();
		resource_conversion_plugins.push_back(vshader_convert);
	}
	update_spinner_step_msec = OS::get_singleton()->get_ticks_msec();
	update_spinner_step_frame = Engine::get_singleton()->get_frames_drawn();
	editor_plugin_screen = nullptr;
	editor_plugins_over = memnew(EditorPluginList);
	editor_plugins_force_over = memnew(EditorPluginList);
	editor_plugins_force_input_forwarding = memnew(EditorPluginList);
	Ref<GDExtensionExportPlugin> gdextension_export_plugin;
	gdextension_export_plugin.instantiate();