### 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_import_settings = memnew(SceneImportSettings);
	gui_base->add_child(scene_import_settings);
	audio_stream_import_settings = memnew(AudioStreamImportSettings);
	gui_base->add_child(audio_stream_import_settings);
	fontdata_import_settings = memnew(DynamicFontImportSettings);
	gui_base->add_child(fontdata_import_settings);
	export_template_manager = memnew(ExportTemplateManager);
	gui_base->add_child(export_template_manager);
	feature_profile_manager = memnew(EditorFeatureProfileManager);
	gui_base->add_child(feature_profile_manager);
	build_profile_manager = memnew(EditorBuildProfileManager);
	gui_base->add_child(build_profile_manager);
	about = memnew(EditorAbout);
	gui_base->add_child(about);
	feature_profile_manager->connect("current_feature_profile_changed", callable_mp(this, &EditorNode::_feature_profile_changed));
#if !defined(ANDROID_ENABLED) && !defined(WEB_ENABLED)
	fbx_importer_manager = memnew(FBXImporterManager);
	gui_base->add_child(fbx_importer_manager);
#endif
	warning = memnew(AcceptDialog);
	warning->set_unparent_when_invisible(true);
	warning->add_button(TTR("Copy Text"), true, "copy");
	warning->connect("custom_action", callable_mp(this, &EditorNode::_copy_warning));
	ED_SHORTCUT("editor/next_tab", TTR("Next Scene Tab"), KeyModifierMask::CMD_OR_CTRL + Key::TAB);
	ED_SHORTCUT("editor/prev_tab", TTR("Previous Scene Tab"), KeyModifierMask::CMD_OR_CTRL + KeyModifierMask::SHIFT + Key::TAB);
	ED_SHORTCUT("editor/filter_files", TTR("Focus FileSystem Filter"), KeyModifierMask::CMD_OR_CTRL + KeyModifierMask::ALT + Key::P);
	command_palette = EditorCommandPalette::get_singleton();
	command_palette->set_title(TTR("Command Palette"));
	gui_base->add_child(command_palette);
	file_menu->add_shortcut(ED_SHORTCUT_AND_COMMAND("editor/new_scene", TTR("New Scene"), KeyModifierMask::CMD_OR_CTRL + Key::N), FILE_NEW_SCENE);