### 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)
for (int i = 0; i < ScriptServer::get_language_count(); i++) {
				ScriptServer::get_language(i)->add_named_global_constant(info.name, Variant());
			}
		}
		autoload_cache.push_back(info);
	}
	for (AutoloadInfo &info : autoload_cache) {
		info.node = _create_autoload(info.path);
		if (info.node) {
			Ref<Script> scr = info.node->get_script();
			info.in_editor = scr.is_valid() && scr->is_tool();
			info.node->set_name(info.name);
		}
		if (info.is_singleton) {
			for (int i = 0; i < ScriptServer::get_language_count(); i++) {
				ScriptServer::get_language(i)->add_named_global_constant(info.name, info.node);
			}
		}
		if (!info.is_singleton && !info.in_editor && info.node != nullptr) {
			memdelete(info.node);
			info.node = nullptr;
		}
	}
	HBoxContainer *hbc = memnew(HBoxContainer);
	add_child(hbc);
	error_message = memnew(Label);
	error_message->hide();
	error_message->set_horizontal_alignment(HORIZONTAL_ALIGNMENT_RIGHT);
	error_message->add_theme_color_override("font_color", EditorNode::get_singleton()->get_editor_theme()->get_color(SNAME("error_color"), EditorStringName(Editor)));