### 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)
_update_theme(true);
			OS::get_singleton()->set_low_processor_usage_mode_sleep_usec(int(EDITOR_GET("interface/editor/low_processor_mode_sleep_usec")));
			get_tree()->get_root()->set_as_audio_listener_3d(false);
			get_tree()->get_root()->set_as_audio_listener_2d(false);
			get_tree()->get_root()->set_snap_2d_transforms_to_pixel(false);
			get_tree()->get_root()->set_snap_2d_vertices_to_pixel(false);
			get_tree()->set_auto_accept_quit(false);
#ifdef ANDROID_ENABLED
			get_tree()->set_quit_on_go_back(false);
#endif
			get_tree()->get_root()->connect("files_dropped", callable_mp(this, &EditorNode::_dropped_files));
			command_palette->register_shortcuts_as_command();
			MessageQueue::get_singleton()->push_callable(callable_mp(this, &EditorNode::_begin_first_scan));
			
		} break;
		case NOTIFICATION_EXIT_TREE: {
			if (progress_dialog) {
				progress_dialog->queue_free();
			}
			if (load_error_dialog) {
				load_error_dialog->queue_free();
			}
			if (execute_output_dialog) {
				execute_output_dialog->queue_free();
			}
			if (warning) {
				warning->queue_free();
			}
			if (accept) {
				accept->queue_free();