### 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 (get_parent_control()) {
		String icon_name = script->get_class();
		if (script->is_built_in()) {
			icon_name += "Internal";
		}
		if (get_parent_control()->has_theme_icon(icon_name, EditorStringName(EditorIcons))) {
			return get_parent_control()->get_editor_theme_icon(icon_name);
		} else if (get_parent_control()->has_theme_icon(script->get_class(), EditorStringName(EditorIcons))) {
			return get_parent_control()->get_editor_theme_icon(script->get_class());
		}
	}
	return Ref<Texture2D>();
}
void ScriptTextEditor::_validate_script() {
	CodeEdit *te = code_editor->get_text_editor();
	String text = te->get_text();
	List<String> fnc;
	warnings.clear();
	errors.clear();
	depended_errors.clear();
	safe_lines.clear();
	if (!script->get_language()->validate(text, script->get_path(), &fnc, &errors, &warnings, &safe_lines)) {
		for (List<ScriptLanguage::ScriptError>::Element *E = errors.front(); E; E = E->next()) {
			if ((E->get().path.is_empty() && !script->get_path().is_empty()) || E->get().path != script->get_path()) {
				depended_errors[E->get().path].push_back(E->get());