### 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 (waiting_for_first_scan) {
		return; 
	}
	Ref<ConfigFile> config;
	config.instantiate();
	
	config->load(EditorPaths::get_singleton()->get_project_settings_dir().path_join("editor_layout.cfg"));
	_save_docks_to_config(config, "docks");
	_save_open_scenes_to_config(config);
	_save_central_editor_layout_to_config(config);
	editor_data.get_plugin_window_layout(config);
	config->save(EditorPaths::get_singleton()->get_project_settings_dir().path_join("editor_layout.cfg"));
}
void EditorNode::_save_docks_to_config(Ref<ConfigFile> p_layout, const String &p_section) {
	for (int i = 0; i < DOCK_SLOT_MAX; i++) {
		String names;
		for (int j = 0; j < dock_slot[i]->get_tab_count(); j++) {
			String name = dock_slot[i]->get_tab_control(j)->get_name();
			if (!names.is_empty()) {
				names += ",";
			}
			names += name;
		}
		String config_key = "dock_" + itos(i + 1);
		if (p_layout->has_section_key(p_section, config_key)) {
			p_layout->erase_section_key(p_section, config_key);
		}
		if (!names.is_empty()) {