### 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 (!Thread::is_main_thread()) {
		set_current_thread_safe_for_nodes(true);
	}
	Ref<Resource> res = _load(load_task.remapped_path, load_task.remapped_path != load_task.local_path ? load_task.local_path : String(), load_task.type_hint, load_task.cache_mode, &load_task.error, load_task.use_sub_threads, &load_task.progress);
	if (mq_override) {
		mq_override->flush();
	}
	thread_load_mutex.lock();
	load_task.resource = res;
	load_task.progress = 1.0; 
	if (load_task.error != OK) {
		load_task.status = THREAD_LOAD_FAILED;
	} else {
		load_task.status = THREAD_LOAD_LOADED;
	}
	if (load_task.cond_var) {
		load_task.cond_var->notify_all();
		memdelete(load_task.cond_var);
		load_task.cond_var = nullptr;
	}
	if (load_task.resource.is_valid()) {
		if (load_task.cache_mode != ResourceFormatLoader::CACHE_MODE_IGNORE) {
			load_task.resource->set_path(load_task.local_path);
		} else if (!load_task.local_path.is_resource_file()) {
			load_task.resource->set_path_cache(load_task.local_path);
		}
		if (load_task.xl_remapped) {
			load_task.resource->set_as_translation_remapped(true);
		}
#ifdef TOOLS_ENABLED