### 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/editor_3d", TTR("Open 3D Editor"), KeyModifierMask::CTRL | Key::F2);
	ED_SHORTCUT_AND_COMMAND("editor/editor_script", TTR("Open Script Editor"), KeyModifierMask::CTRL | Key::F3);
	ED_SHORTCUT_AND_COMMAND("editor/editor_assetlib", TTR("Open Asset Library"), KeyModifierMask::CTRL | Key::F4);
	ED_SHORTCUT_OVERRIDE("editor/editor_2d", "macos", KeyModifierMask::META | KeyModifierMask::CTRL | Key::KEY_1);
	ED_SHORTCUT_OVERRIDE("editor/editor_3d", "macos", KeyModifierMask::META | KeyModifierMask::CTRL | Key::KEY_2);
	ED_SHORTCUT_OVERRIDE("editor/editor_script", "macos", KeyModifierMask::META | KeyModifierMask::CTRL | Key::KEY_3);
	ED_SHORTCUT_OVERRIDE("editor/editor_assetlib", "macos", KeyModifierMask::META | KeyModifierMask::CTRL | Key::KEY_4);
	ED_SHORTCUT_AND_COMMAND("editor/editor_next", TTR("Open the next Editor"));
	ED_SHORTCUT_AND_COMMAND("editor/editor_prev", TTR("Open the previous Editor"));
	screenshot_timer = memnew(Timer);
	screenshot_timer->set_one_shot(true);
	screenshot_timer->set_wait_time(settings_menu->get_submenu_popup_delay() + 0.1f);
	screenshot_timer->connect("timeout", callable_mp(this, &EditorNode::_request_screenshot));
	add_child(screenshot_timer);
	screenshot_timer->set_owner(get_owner());
	
	int max_w = MAX(project_run_bar->get_minimum_size().x + right_menu_hb->get_minimum_size().x, main_menu->get_minimum_size().x);
	left_spacer->set_custom_minimum_size(Size2(MAX(0, max_w - main_menu->get_minimum_size().x), 0));
	right_spacer->set_custom_minimum_size(Size2(MAX(0, max_w - project_run_bar->get_minimum_size().x - right_menu_hb->get_minimum_size().x), 0));
	
	if (can_expand) {
		DisplayServer::get_singleton()->process_events();
		DisplayServer::get_singleton()->window_set_flag(DisplayServer::WINDOW_FLAG_EXTEND_TO_TITLE, true, DisplayServer::MAIN_WINDOW_ID);
		title_bar->set_can_move_window(true);
	}
	String exec = OS::get_singleton()->get_executable_path();
	
	EditorSettings::get_singleton()->set_project_metadata("editor_metadata", "executable_path", exec);
}
EditorNode::~EditorNode() {