### 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)
if (!bool(EDITOR_GET("text_editor/external/use_external_editor"))) {
		return;
	}
	ERR_FAIL_NULL(get_tree());
	HashSet<Ref<Script>> scripts;
	Node *base = get_tree()->get_edited_scene_root();
	if (base) {
		_find_changed_scripts_for_external_editor(base, base, scripts);
	}
	for (const Ref<Script> &E : scripts) {
		Ref<Script> scr = E;
		if (p_for_script.is_valid() && p_for_script != scr) {
			continue;
		}
		if (scr->is_built_in()) {
			continue; 
		}
		uint64_t last_date = scr->get_last_modified_time();
		uint64_t date = FileAccess::get_modified_time(scr->get_path());
		if (last_date != date) {
			Ref<Script> rel_scr = ResourceLoader::load(scr->get_path(), scr->get_class(), ResourceFormatLoader::CACHE_MODE_IGNORE);
			ERR_CONTINUE(!rel_scr.is_valid());
			scr->set_source_code(rel_scr->get_source_code());
			scr->set_last_modified_time(rel_scr->get_last_modified_time());
			scr->update_exports();
			trigger_live_script_reload();
		}
	}
}
void ScriptTextEditor::_code_complete_scripts(void *p_ud, const String &p_code, List<ScriptLanguage::CodeCompletionOption> *r_options, bool &r_force) {