### 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)
last_modified_string = vformat(TTRN("%d minute ago", "%d minutes ago", last_modified_seconds / 60), last_modified_seconds / 60);
			} else {
				last_modified_string = vformat(TTRN("%d hour ago", "%d hours ago", last_modified_seconds / 3600), last_modified_seconds / 3600);
			}
			unsaved_message = vformat(TTR("Scene \"%s\" has unsaved changes.\nLast saved: %s."), scene_filename, last_modified_string);
		}
	} else {
		
		for (int i = 0; i < editor_data.get_editor_plugin_count(); i++) {
			unsaved_message = editor_data.get_editor_plugin(i)->get_unsaved_status(scene_filename);
			if (!unsaved_message.is_empty()) {
				break;
			}
		}
	}
	if (!unsaved_message.is_empty()) {
		if (scene_tabs->get_current_tab() != p_tab) {
			_set_current_scene(p_tab);
		}
		save_confirmation->set_ok_button_text(TTR("Save & Close"));
		save_confirmation->set_text(unsaved_message + "\n\n" + TTR("Save before closing?"));
		save_confirmation->reset_size();
		save_confirmation->popup_centered();
	} else {
		_discard_changes();
	}
	save_editor_layout_delayed();
	scene_tabs->update_scene_tabs();
}
Button *EditorNode::add_bottom_panel_item(String p_text, Control *p_item) {