### 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)
Node *selected_node = nullptr;
		if (current_obj->is_class("MultiNodeEdit")) {
			Node *scene = get_edited_scene();
			if (scene) {
				MultiNodeEdit *multi_node_edit = Object::cast_to<MultiNodeEdit>(current_obj);
				int node_count = multi_node_edit->get_node_count();
				if (node_count > 0) {
					List<Node *> multi_nodes;
					for (int node_index = 0; node_index < node_count; ++node_index) {
						Node *node = scene->get_node(multi_node_edit->get_node(node_index));
						if (node) {
							multi_nodes.push_back(node);
						}
					}
					if (!multi_nodes.is_empty()) {
						
						multi_nodes.sort_custom<Node::Comparator>();
						selected_node = multi_nodes.front()->get();
					}
				}
			}
		}
		InspectorDock::get_inspector_singleton()->edit(current_obj);
		NodeDock::get_singleton()->set_node(nullptr);
		SceneTreeDock::get_singleton()->set_selected(selected_node);
		InspectorDock::get_singleton()->update(nullptr);
	}
	InspectorDock::get_singleton()->set_info(
			info_is_warning ? TTR("Changes may be lost!") : TTR("This object is read-only."),
			editable_info,