### 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)
load_task.resource->set_edited(false);
		if (timestamp_on_load) {
			uint64_t mt = FileAccess::get_modified_time(load_task.remapped_path);
			
			load_task.resource->set_last_modified_time(mt);
		}
#endif
		if (_loaded_callback) {
			_loaded_callback(load_task.resource, load_task.local_path);
		}
	}
	thread_load_mutex.unlock();
	if (load_nesting == 0) {
		if (mq_override) {
			memdelete(mq_override);
		}
		memdelete(load_paths_stack);
	}
}
static String _validate_local_path(const String &p_path) {
	ResourceUID::ID uid = ResourceUID::get_singleton()->text_to_id(p_path);
	if (uid != ResourceUID::INVALID_ID) {
		return ResourceUID::get_singleton()->get_id_path(uid);
	} else if (p_path.is_relative_path()) {
		return "res://" + p_path;
	} else {
		return ProjectSettings::get_singleton()->localize_path(p_path);
	}
}
Error ResourceLoader::load_threaded_request(const String &p_path, const String &p_type_hint, bool p_use_sub_threads, ResourceFormatLoader::CacheMode p_cache_mode) {