### 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 (p_editor->has_main_screen()) {
		Button *tb = memnew(Button);
		tb->set_flat(true);
		tb->set_toggle_mode(true);
		tb->connect("pressed", callable_mp(singleton, &EditorNode::editor_select).bind(singleton->main_editor_buttons.size()));
		tb->set_name(p_editor->get_name());
		tb->set_text(p_editor->get_name());
		Ref<Texture2D> icon = p_editor->get_icon();
		if (icon.is_valid()) {
			tb->set_icon(icon);
			
			icon->connect_changed(callable_mp((Control *)tb, &Control::update_minimum_size));
		} else if (singleton->theme->has_icon(p_editor->get_name(), EditorStringName(EditorIcons))) {
			tb->set_icon(singleton->theme->get_icon(p_editor->get_name(), EditorStringName(EditorIcons)));
		}
		tb->add_theme_font_override("font", singleton->theme->get_font(SNAME("main_button_font"), EditorStringName(EditorFonts)));
		tb->add_theme_font_size_override("font_size", singleton->theme->get_font_size(SNAME("main_button_font_size"), EditorStringName(EditorFonts)));
		singleton->main_editor_buttons.push_back(tb);
		singleton->main_editor_button_hb->add_child(tb);
		singleton->editor_table.push_back(p_editor);
		singleton->distraction_free->move_to_front();
	}
	singleton->editor_data.add_editor_plugin(p_editor);
	singleton->add_child(p_editor);
	if (p_config_changed) {
		p_editor->enable_plugin();
	}
}
void EditorNode::remove_editor_plugin(EditorPlugin *p_editor, bool p_config_changed) {