### 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)
info_is_warning);
	Object *editor_owner = is_node ? (Object *)SceneTreeDock::get_singleton() : is_resource ? (Object *)InspectorDock::get_inspector_singleton()
																							: (Object *)this;
	
	if (!inspector_only) {
		EditorPlugin *main_plugin = editor_data.get_handling_main_editor(current_obj);
		int plugin_index = 0;
		for (; plugin_index < editor_table.size(); plugin_index++) {
			if (editor_table[plugin_index] == main_plugin) {
				if (!main_editor_buttons[plugin_index]->is_visible()) {
					main_plugin = nullptr; 
				}
				break;
			}
		}
		ObjectID editor_owner_id = editor_owner->get_instance_id();
		if (main_plugin && !skip_main_plugin) {
			
			Resource *current_res = Object::cast_to<Resource>(current_obj);
			if (main_plugin->get_name() == "Script" && current_res && !current_res->is_built_in() && (bool(EDITOR_GET("text_editor/external/use_external_editor")) || overrides_external_editor(current_obj))) {
				if (!changing_scene) {
					main_plugin->edit(current_obj);
				}
			}
			else if (main_plugin != editor_plugin_screen && (!ScriptEditor::get_singleton() || !ScriptEditor::get_singleton()->is_visible_in_tree() || ScriptEditor::get_singleton()->can_take_away_focus())) {
				
				editor_plugin_screen->edit(nullptr);
				active_plugins[editor_owner_id].erase(editor_plugin_screen);
				
				editor_select(plugin_index);