### 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)
method->set_text(p_method);
	tree->clear();
	TreeItem *root = tree->create_item();
	for (int i = 0; i < p_nodes.size(); i++) {
		List<Connection> all_connections;
		p_nodes[i]->get_signals_connected_to_this(&all_connections);
		for (const Connection &connection : all_connections) {
			if (connection.callable.get_method() != p_method) {
				continue;
			}
			TreeItem *node_item = tree->create_item(root);
			node_item->set_text(0, Object::cast_to<Node>(connection.signal.get_object())->get_name());
			node_item->set_icon(0, EditorNode::get_singleton()->get_object_icon(connection.signal.get_object(), "Node"));
			node_item->set_selectable(0, false);
			node_item->set_editable(0, false);
			node_item->set_text(1, connection.signal.get_name());
			Control *p = Object::cast_to<Control>(get_parent());
			node_item->set_icon(1, p->get_editor_theme_icon(SNAME("Slot")));
			node_item->set_selectable(1, false);
			node_item->set_editable(1, false);
			node_item->set_text(2, Object::cast_to<Node>(connection.callable.get_object())->get_name());
			node_item->set_icon(2, EditorNode::get_singleton()->get_object_icon(connection.callable.get_object(), "Node"));
			node_item->set_selectable(2, false);
			node_item->set_editable(2, false);
		}
	}
	popup_centered(Size2(600, 300) * EDSCALE);
}
ConnectionInfoDialog::ConnectionInfoDialog() {