### 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)
if (DisplayServer::get_singleton()->window_can_draw()) {
				ProjectSettings::get_singleton()->save();
			}
			_titlebar_resized();
			
			CanvasItemEditor::ThemePreviewMode theme_preview_mode = (CanvasItemEditor::ThemePreviewMode)(int)EditorSettings::get_singleton()->get_project_metadata("2d_editor", "theme_preview", CanvasItemEditor::THEME_PREVIEW_PROJECT);
			update_preview_themes(theme_preview_mode);
			
		} break;
		case NOTIFICATION_APPLICATION_FOCUS_IN: {
			
			OS::get_singleton()->set_low_processor_usage_mode_sleep_usec(int(EDITOR_GET("interface/editor/low_processor_mode_sleep_usec")));
			EditorFileSystem::get_singleton()->scan_changes();
			_scan_external_changes();
			GDExtensionManager *gdextension_manager = GDExtensionManager::get_singleton();
			callable_mp(gdextension_manager, &GDExtensionManager::reload_extensions).call_deferred();
		} break;
		case NOTIFICATION_APPLICATION_FOCUS_OUT: {
			
			if (EDITOR_GET("interface/editor/save_on_focus_loss")) {
				_menu_option_confirm(FILE_SAVE_SCENE, false);
			}
			
			OS::get_singleton()->set_low_processor_usage_mode_sleep_usec(int(EDITOR_GET("interface/editor/unfocused_low_processor_mode_sleep_usec")));
		} break;
		case NOTIFICATION_WM_ABOUT: {
			show_about();
		} break;
		case NOTIFICATION_WM_CLOSE_REQUEST: {
			_menu_option_confirm(FILE_QUIT, false);