### 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)
scene_tabs->connect("tab_closed", callable_mp(this, &EditorNode::_scene_tab_closed));
	distraction_free = memnew(Button);
	distraction_free->set_flat(true);
	ED_SHORTCUT_AND_COMMAND("editor/distraction_free_mode", TTR("Distraction Free Mode"), KeyModifierMask::CTRL | KeyModifierMask::SHIFT | Key::F11);
	ED_SHORTCUT_OVERRIDE("editor/distraction_free_mode", "macos", KeyModifierMask::META | KeyModifierMask::CTRL | Key::D);
	distraction_free->set_shortcut(ED_GET_SHORTCUT("editor/distraction_free_mode"));
	distraction_free->set_tooltip_text(TTR("Toggle distraction-free mode."));
	distraction_free->set_toggle_mode(true);
	scene_tabs->add_extra_button(distraction_free);
	distraction_free->connect("pressed", callable_mp(this, &EditorNode::_toggle_distraction_free_mode));
	scene_root_parent = memnew(PanelContainer);
	scene_root_parent->set_custom_minimum_size(Size2(0, 80) * EDSCALE);
	scene_root_parent->add_theme_style_override("panel", theme->get_stylebox(SNAME("Content"), EditorStringName(EditorStyles)));
	scene_root_parent->set_draw_behind_parent(true);
	srt->add_child(scene_root_parent);
	scene_root_parent->set_v_size_flags(Control::SIZE_EXPAND_FILL);
	scene_root = memnew(SubViewport);
	scene_root->set_embedding_subwindows(true);
	scene_root->set_disable_3d(true);
	scene_root->set_disable_input(true);
	scene_root->set_as_audio_listener_2d(true);
	main_screen_vbox = memnew(VBoxContainer);
	main_screen_vbox->set_name("MainScreen");
	main_screen_vbox->set_v_size_flags(Control::SIZE_EXPAND_FILL);
	main_screen_vbox->add_theme_constant_override("separation", 0);
	scene_root_parent->add_child(main_screen_vbox);
	bool global_menu = !bool(EDITOR_GET("interface/editor/use_embedded_menu")) && DisplayServer::get_singleton()->has_feature(DisplayServer::FEATURE_GLOBAL_MENU);
	bool can_expand = bool(EDITOR_GET("interface/editor/expand_to_title")) && DisplayServer::get_singleton()->has_feature(DisplayServer::FEATURE_EXTEND_TO_TITLE);
	if (can_expand) {