### 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)
ERR_FAIL_NULL(p_dock);
	Size2 borders = Size2(4, 4) * EDSCALE;
	
	Size2 dock_size = p_dock->get_size() + borders * 2;
	Point2 dock_screen_pos = p_dock->get_screen_position();
	int dock_index = p_dock->get_index() - 1;
	dock_slot[p_slot_index]->remove_child(p_dock);
	WindowWrapper *wrapper = memnew(WindowWrapper);
	wrapper->set_window_title(vformat(TTR("%s - Godot Engine"), p_dock->get_name()));
	wrapper->set_margins_enabled(true);
	gui_base->add_child(wrapper);
	wrapper->set_wrapped_control(p_dock);
	wrapper->set_meta("dock_slot", p_slot_index);
	wrapper->set_meta("dock_index", dock_index);
	wrapper->set_meta("dock_name", p_dock->get_name().operator String());
	p_dock->show();
	wrapper->connect("window_close_requested", callable_mp(this, &EditorNode::_dock_floating_close_request).bind(wrapper));
	dock_select_popup->hide();
	if (p_show_window) {
		wrapper->restore_window(Rect2i(dock_screen_pos, dock_size), get_window()->get_current_screen());
	}
	_update_dock_containers();
	floating_docks.push_back(wrapper);
	_edit_current();
}
void EditorNode::_update_dock_containers() {