### 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)
int warning_nb = warnings.size();
	warnings_panel->clear();
	bool has_connections_table = false;
	
	if (GLOBAL_GET("debug/gdscript/warnings/enable").booleanize()) {
		Node *base = get_tree()->get_edited_scene_root();
		if (base && missing_connections.size() > 0) {
			has_connections_table = true;
			warnings_panel->push_table(1);
			for (const Connection &connection : missing_connections) {
				String base_path = base->get_name();
				String source_path = base == connection.signal.get_object() ? base_path : base_path + "/" + base->get_path_to(Object::cast_to<Node>(connection.signal.get_object()));
				String target_path = base == connection.callable.get_object() ? base_path : base_path + "/" + base->get_path_to(Object::cast_to<Node>(connection.callable.get_object()));
				warnings_panel->push_cell();
				warnings_panel->push_color(warnings_panel->get_theme_color(SNAME("warning_color"), EditorStringName(Editor)));
				warnings_panel->add_text(vformat(TTR("Missing connected method '%s' for signal '%s' from node '%s' to node '%s'."), connection.callable.get_method(), connection.signal.get_name(), source_path, target_path));
				warnings_panel->pop(); 
				warnings_panel->pop(); 
			}
			warnings_panel->pop(); 
			warning_nb += missing_connections.size();
		}
	}
	code_editor->set_warning_count(warning_nb);
	if (has_connections_table) {
		warnings_panel->add_newline();
	}