### 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)
switch (p_what) {
		case NOTIFICATION_POSTINITIALIZE: {
			EditorHelp::generate_doc();
		} break;
		case NOTIFICATION_PROCESS: {
			if (opening_prev && !confirmation->is_visible()) {
				opening_prev = false;
			}
			bool global_unsaved = EditorUndoRedoManager::get_singleton()->is_history_unsaved(EditorUndoRedoManager::GLOBAL_HISTORY);
			bool scene_or_global_unsaved = global_unsaved || EditorUndoRedoManager::get_singleton()->is_history_unsaved(editor_data.get_current_edited_scene_history_id());
			if (unsaved_cache != scene_or_global_unsaved) {
				unsaved_cache = scene_or_global_unsaved;
				_update_title();
			}
			if (editor_data.is_scene_changed(-1)) {
				scene_tabs->update_scene_tabs();
			}
			
			uint64_t frame = Engine::get_singleton()->get_frames_drawn();
			uint64_t tick = OS::get_singleton()->get_ticks_msec();
			if (frame != update_spinner_step_frame && (tick - update_spinner_step_msec) > (1000 / 8)) {
				update_spinner_step++;
				if (update_spinner_step >= 8) {
					update_spinner_step = 0;
				}
				update_spinner_step_msec = tick;