### 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)
help_menu->add_icon_shortcut(theme->get_icon(SNAME("Heart"), EditorStringName(EditorIcons)), ED_SHORTCUT_AND_COMMAND("editor/support_development", TTR("Support Godot Development")), HELP_SUPPORT_GODOT_DEVELOPMENT);
	
	Control *right_spacer = memnew(Control);
	right_spacer->set_mouse_filter(Control::MOUSE_FILTER_PASS);
	right_spacer->set_h_size_flags(Control::SIZE_EXPAND_FILL);
	title_bar->add_child(right_spacer);
	project_run_bar = memnew(EditorRunBar);
	title_bar->add_child(project_run_bar);
	project_run_bar->connect("play_pressed", callable_mp(this, &EditorNode::_project_run_started));
	project_run_bar->connect("stop_pressed", callable_mp(this, &EditorNode::_project_run_stopped));
	HBoxContainer *right_menu_hb = memnew(HBoxContainer);
	title_bar->add_child(right_menu_hb);
	renderer = memnew(OptionButton);
	renderer->set_visible(true);
	renderer->set_flat(true);
	renderer->set_fit_to_longest_item(false);
	renderer->set_focus_mode(Control::FOCUS_NONE);
	renderer->connect("item_selected", callable_mp(this, &EditorNode::_renderer_selected));
	renderer->add_theme_font_override("font", theme->get_font(SNAME("bold"), EditorStringName(EditorFonts)));
	renderer->add_theme_font_size_override("font_size", theme->get_font_size(SNAME("bold_size"), EditorStringName(EditorFonts)));
	renderer->set_tooltip_text(TTR("Choose a renderer."));
	right_menu_hb->add_child(renderer);
	if (can_expand) {
		
		right_menu_spacer = memnew(Control);
		right_menu_spacer->set_mouse_filter(Control::MOUSE_FILTER_PASS);
		title_bar->add_child(right_menu_spacer);
	}
	String current_renderer = GLOBAL_GET("rendering/renderer/rendering_method");
	PackedStringArray renderers = ProjectSettings::get_singleton()->get_custom_property_info().get(StringName("rendering/renderer/rendering_method")).hint_string.split(",", false);