### 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)
return ERR_FILE_NOT_FOUND;
	}
	int prev = editor_data.get_edited_scene();
	int idx = editor_data.add_edited_scene(-1);
	if (!editor_data.get_edited_scene_root() && editor_data.get_edited_scene_count() == 2) {
		_remove_edited_scene();
	} else if (p_silent_change_tab) {
		_set_current_scene_nocheck(idx);
	} else {
		_set_current_scene(idx);
	}
	dependency_errors.clear();
	Error err;
	Ref<PackedScene> sdata = ResourceLoader::load(lpath, "", ResourceFormatLoader::CACHE_MODE_REPLACE, &err);
	if (!p_ignore_broken_deps && dependency_errors.has(lpath)) {
		current_menu_option = -1;
		Vector<String> errors;
		for (const String &E : dependency_errors[lpath]) {
			errors.push_back(E);
		}
		dependency_error->show(DependencyErrorDialog::MODE_SCENE, lpath, errors);
		opening_prev = false;
		if (prev != -1) {
			_set_current_scene(prev);
			editor_data.remove_scene(idx);
		}
		return ERR_FILE_MISSING_DEPENDENCIES;
	}
	if (!sdata.is_valid()) {
		_dialog_display_load_error(lpath, err);