### 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)
}
	singleton->editor_plugins_over->remove_plugin(p_editor);
	singleton->editor_plugins_force_over->remove_plugin(p_editor);
	singleton->editor_plugins_force_input_forwarding->remove_plugin(p_editor);
	singleton->remove_child(p_editor);
	singleton->editor_data.remove_editor_plugin(p_editor);
	for (KeyValue<ObjectID, HashSet<EditorPlugin *>> &kv : singleton->active_plugins) {
		kv.value.erase(p_editor);
	}
}
void EditorNode::add_extension_editor_plugin(const StringName &p_class_name) {
	ERR_FAIL_COND_MSG(!ClassDB::class_exists(p_class_name), vformat("No such editor plugin registered: %s", p_class_name));
	ERR_FAIL_COND_MSG(!ClassDB::is_parent_class(p_class_name, SNAME("EditorPlugin")), vformat("Class is not an editor plugin: %s", p_class_name));
	ERR_FAIL_COND_MSG(singleton->editor_data.has_extension_editor_plugin(p_class_name), vformat("Editor plugin already added for class: %s", p_class_name));
	EditorPlugin *plugin = Object::cast_to<EditorPlugin>(ClassDB::instantiate(p_class_name));
	singleton->editor_data.add_extension_editor_plugin(p_class_name, plugin);
	add_editor_plugin(plugin);
}
void EditorNode::remove_extension_editor_plugin(const StringName &p_class_name) {
	
	if (singleton->exiting) {
		return;
	}
	ERR_FAIL_COND_MSG(!singleton->editor_data.has_extension_editor_plugin(p_class_name), vformat("No editor plugin added for class: %s", p_class_name));
	EditorPlugin *plugin = singleton->editor_data.get_extension_editor_plugin(p_class_name);
	remove_editor_plugin(plugin);
	memdelete(plugin);
	singleton->editor_data.remove_extension_editor_plugin(p_class_name);
}
void EditorNode::_update_addon_config() {