### 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)
project_menu->set_item_submenu(project_menu->get_item_index(VCS_MENU), "Version Control");
	add_editor_plugin(memnew(AudioBusesEditorPlugin(audio_bus_editor)));
	for (int i = 0; i < EditorPlugins::get_plugin_count(); i++) {
		add_editor_plugin(EditorPlugins::create(i));
	}
	for (const StringName &extension_class_name : GDExtensionEditorPlugins::get_extension_classes()) {
		add_extension_editor_plugin(extension_class_name);
	}
	GDExtensionEditorPlugins::editor_node_add_plugin = &EditorNode::add_extension_editor_plugin;
	GDExtensionEditorPlugins::editor_node_remove_plugin = &EditorNode::remove_extension_editor_plugin;
	for (int i = 0; i < plugin_init_callback_count; i++) {
		plugin_init_callbacks[i]();
	}
	resource_preview->add_preview_generator(Ref<EditorTexturePreviewPlugin>(memnew(EditorTexturePreviewPlugin)));
	resource_preview->add_preview_generator(Ref<EditorImagePreviewPlugin>(memnew(EditorImagePreviewPlugin)));
	resource_preview->add_preview_generator(Ref<EditorPackedScenePreviewPlugin>(memnew(EditorPackedScenePreviewPlugin)));
	resource_preview->add_preview_generator(Ref<EditorMaterialPreviewPlugin>(memnew(EditorMaterialPreviewPlugin)));
	resource_preview->add_preview_generator(Ref<EditorScriptPreviewPlugin>(memnew(EditorScriptPreviewPlugin)));
	resource_preview->add_preview_generator(Ref<EditorAudioStreamPreviewPlugin>(memnew(EditorAudioStreamPreviewPlugin)));
	resource_preview->add_preview_generator(Ref<EditorMeshPreviewPlugin>(memnew(EditorMeshPreviewPlugin)));
	resource_preview->add_preview_generator(Ref<EditorBitmapPreviewPlugin>(memnew(EditorBitmapPreviewPlugin)));
	resource_preview->add_preview_generator(Ref<EditorFontPreviewPlugin>(memnew(EditorFontPreviewPlugin)));
	resource_preview->add_preview_generator(Ref<EditorGradientPreviewPlugin>(memnew(EditorGradientPreviewPlugin)));
	{
		Ref<StandardMaterial3DConversionPlugin> spatial_mat_convert;
		spatial_mat_convert.instantiate();
		resource_conversion_plugins.push_back(spatial_mat_convert);
		Ref<ORMMaterial3DConversionPlugin> orm_mat_convert;
		orm_mat_convert.instantiate();
		resource_conversion_plugins.push_back(orm_mat_convert);