### 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)
Node *scene = editor_data.get_edited_scene_root(scene_idx);
			if (scene && !scene->get_scene_file_path().is_empty()) {
				if (DirAccess::exists(scene->get_scene_file_path().get_base_dir())) {
					if (scene_idx != editor_data.get_edited_scene()) {
						_save_scene_with_preview(scene->get_scene_file_path(), scene_idx);
					} else {
						_save_scene_with_preview(scene->get_scene_file_path());
					}
					if (scene_idx != -1) {
						_discard_changes();
					}
					save_editor_layout_delayed();
				} else {
					show_save_accept(vformat(TTR("%s no longer exists! Please specify a new save location."), scene->get_scene_file_path().get_base_dir()), TTR("OK"));
				}
				break;
			}
			[[fallthrough]];
		}
		case FILE_SAVE_AS_SCENE: {
			int scene_idx = (p_option == FILE_SAVE_SCENE || p_option == FILE_SAVE_AS_SCENE) ? -1 : tab_closing_idx;
			Node *scene = editor_data.get_edited_scene_root(scene_idx);
			if (!scene) {
				if (p_option == FILE_SAVE_SCENE) {
					
					
					ScriptEditor::get_singleton()->save_current_script();
				}
				const int saved = _save_external_resources();
				if (saved > 0) {