### 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)
item->set_text(0, name);
		item->set_editable(0, true);
		item->set_text(1, scr_path);
		item->set_selectable(1, true);
		item->set_cell_mode(2, TreeItem::CELL_MODE_CHECK);
		item->set_editable(2, true);
		item->set_text(2, TTR("Enable"));
		item->set_checked(2, info.is_singleton);
		item->add_button(3, get_editor_theme_icon(SNAME("Load")), BUTTON_OPEN);
		item->add_button(3, get_editor_theme_icon(SNAME("MoveUp")), BUTTON_MOVE_UP);
		item->add_button(3, get_editor_theme_icon(SNAME("MoveDown")), BUTTON_MOVE_DOWN);
		item->add_button(3, get_editor_theme_icon(SNAME("Remove")), BUTTON_DELETE);
		item->set_selectable(3, false);
	}
	
	for (KeyValue<String, AutoloadInfo> &E : to_remove) {
		AutoloadInfo &info = E.value;
		if (info.is_singleton) {
			for (int i = 0; i < ScriptServer::get_language_count(); i++) {
				ScriptServer::get_language(i)->remove_named_global_constant(info.name);
			}
		}
		if (info.in_editor) {
			ERR_CONTINUE(!info.node);
			get_tree()->get_root()->call_deferred(SNAME("remove_child"), info.node);
		}
		if (info.node) {
			info.node->queue_free();
			info.node = nullptr;
		}