### 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)
dependency_errors.clear();
	Error err;
	Ref<Resource> res;
	if (ResourceLoader::exists(p_resource, "")) {
		res = ResourceLoader::load(p_resource, "", ResourceFormatLoader::CACHE_MODE_REUSE, &err);
	} else if (textfile_extensions.has(p_resource.get_extension())) {
		res = ScriptEditor::get_singleton()->open_file(p_resource);
	}
	ERR_FAIL_COND_V(!res.is_valid(), ERR_CANT_OPEN);
	if (!p_ignore_broken_deps && dependency_errors.has(p_resource)) {
		Vector<String> errors;
		for (const String &E : dependency_errors[p_resource]) {
			errors.push_back(E);
		}
		dependency_error->show(DependencyErrorDialog::MODE_RESOURCE, p_resource, errors);
		dependency_errors.erase(p_resource);
		return ERR_FILE_MISSING_DEPENDENCIES;
	}
	InspectorDock::get_singleton()->edit_resource(res);
	return OK;
}
void EditorNode::edit_node(Node *p_node) {
	push_item(p_node);
}
void EditorNode::edit_resource(const Ref<Resource> &p_resource) {