### 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)
layout_dialog = memnew(EditorLayoutsDialog);
	gui_base->add_child(layout_dialog);
	layout_dialog->set_hide_on_ok(false);
	layout_dialog->set_size(Size2(225, 270) * EDSCALE);
	layout_dialog->connect("name_confirmed", callable_mp(this, &EditorNode::_dialog_action));
	update_spinner = memnew(MenuButton);
	right_menu_hb->add_child(update_spinner);
	update_spinner->set_icon(theme->get_icon(SNAME("Progress1"), EditorStringName(EditorIcons)));
	update_spinner->get_popup()->connect("id_pressed", callable_mp(this, &EditorNode::_menu_option));
	PopupMenu *p = update_spinner->get_popup();
	p->add_radio_check_item(TTR("Update Continuously"), SETTINGS_UPDATE_CONTINUOUSLY);
	p->add_radio_check_item(TTR("Update When Changed"), SETTINGS_UPDATE_WHEN_CHANGED);
	p->add_separator();
	p->add_item(TTR("Hide Update Spinner"), SETTINGS_UPDATE_SPINNER_HIDE);
	_update_update_spinner();
	
	memnew(SceneTreeDock(scene_root, editor_selection, editor_data));
	memnew(InspectorDock(editor_data));
	memnew(ImportDock);
	memnew(NodeDock);
	FileSystemDock *filesystem_dock = memnew(FileSystemDock);
	filesystem_dock->connect("inherit", callable_mp(this, &EditorNode::_inherit_request));
	filesystem_dock->connect("instantiate", callable_mp(this, &EditorNode::_instantiate_request));
	filesystem_dock->connect("display_mode_changed", callable_mp(this, &EditorNode::_save_editor_layout));
	get_project_settings()->connect_filesystem_dock_signals(filesystem_dock);
	history_dock = memnew(HistoryDock);
	
	dock_slot[DOCK_SLOT_LEFT_UR]->add_child(SceneTreeDock::get_singleton());
	dock_slot[DOCK_SLOT_LEFT_UR]->set_tab_title(dock_slot[DOCK_SLOT_LEFT_UR]->get_tab_idx_from_control(SceneTreeDock::get_singleton()), TTR("Scene"));