### 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)
ED_SHORTCUT_AND_COMMAND("editor/quit_to_project_list", TTR("Quit to Project List"), KeyModifierMask::CTRL + KeyModifierMask::SHIFT + Key::Q);
	ED_SHORTCUT_OVERRIDE("editor/quit_to_project_list", "macos", KeyModifierMask::META + KeyModifierMask::CTRL + KeyModifierMask::ALT + Key::Q);
	project_menu->add_shortcut(ED_GET_SHORTCUT("editor/quit_to_project_list"), RUN_PROJECT_MANAGER, true);
	
	HBoxContainer *left_spacer = memnew(HBoxContainer);
	left_spacer->set_mouse_filter(Control::MOUSE_FILTER_PASS);
	left_spacer->set_h_size_flags(Control::SIZE_EXPAND_FILL);
	title_bar->add_child(left_spacer);
	if (can_expand && global_menu) {
		project_title = memnew(Label);
		project_title->add_theme_font_override("font", theme->get_font(SNAME("bold"), EditorStringName(EditorFonts)));
		project_title->add_theme_font_size_override("font_size", theme->get_font_size(SNAME("bold_size"), EditorStringName(EditorFonts)));
		project_title->set_focus_mode(Control::FOCUS_NONE);
		project_title->set_text_overrun_behavior(TextServer::OVERRUN_TRIM_ELLIPSIS);
		project_title->set_vertical_alignment(VERTICAL_ALIGNMENT_CENTER);
		project_title->set_h_size_flags(Control::SIZE_EXPAND_FILL);
		project_title->set_mouse_filter(Control::MOUSE_FILTER_PASS);
		left_spacer->add_child(project_title);
	}
	main_editor_button_hb = memnew(HBoxContainer);
	title_bar->add_child(main_editor_button_hb);
	
	debug_menu = memnew(PopupMenu);
	debug_menu->set_name(TTR("Debug"));
	main_menu->add_child(debug_menu);
	settings_menu = memnew(PopupMenu);
	settings_menu->set_name(TTR("Editor"));
	main_menu->add_child(settings_menu);
	ED_SHORTCUT_AND_COMMAND("editor/editor_settings", TTR("Editor Settings..."));
	ED_SHORTCUT_OVERRIDE("editor/editor_settings", "macos", KeyModifierMask::META + Key::COMMA);