### 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)
show_accept(
							vformat(TTR("The current scene has no root node, but %d modified external resource(s) were saved anyway."), saved),
							TTR("OK"));
				} else if (p_option == FILE_SAVE_AS_SCENE) {
					
					show_accept(
							TTR("A root node is required to save the scene. You can add a root node using the Scene tree dock."),
							TTR("OK"));
				}
				break;
			}
			file->set_file_mode(EditorFileDialog::FILE_MODE_SAVE_FILE);
			List<String> extensions;
			Ref<PackedScene> sd = memnew(PackedScene);
			ResourceSaver::get_recognized_extensions(sd, &extensions);
			file->clear_filters();
			for (int i = 0; i < extensions.size(); i++) {
				file->add_filter("*." + extensions[i], extensions[i].to_upper());
			}
			if (!scene->get_scene_file_path().is_empty()) {
				String path = scene->get_scene_file_path();
				file->set_current_path(path);
				if (extensions.size()) {
					String ext = path.get_extension().to_lower();
					if (extensions.find(ext) == nullptr) {
						file->set_current_path(path.replacen("." + ext, "." + extensions.front()->get()));
					}
				}
			} else if (extensions.size()) {
				String root_name = scene->get_name();