### 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 (!is_inside_tree()) {
		defer_load_scene = p_scene;
		return OK;
	}
	if (!p_set_inherited) {
		for (int i = 0; i < editor_data.get_edited_scene_count(); i++) {
			if (editor_data.get_scene_path(i) == p_scene) {
				_set_current_scene(i);
				return OK;
			}
		}
		if (!p_force_open_imported && FileAccess::exists(p_scene + ".import")) {
			open_imported->set_text(vformat(TTR("Scene '%s' was automatically imported, so it can't be modified.\nTo make changes to it, a new inherited scene can be created."), p_scene.get_file()));
			open_imported->popup_centered();
			new_inherited_button->grab_focus();
			open_import_request = p_scene;
			return OK;
		}
	}
	if (p_clear_errors) {
		load_errors->clear();
	}
	String lpath = ProjectSettings::get_singleton()->localize_path(p_scene);
	if (!lpath.begins_with("res:")) {
		show_accept(TTR("Error loading scene, it must be inside the project path. Use 'Import' to open the scene, then save it inside the project path."), TTR("OK"));
		opening_prev = false;