### 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 (obj->is_ref_counted()) {
		obj_ref = Ref<RefCounted>(Object::cast_to<RefCounted>(obj));
	}
	obj->set_script(script);
	GDScriptInstance *instance = static_cast<GDScriptInstance *>(obj->get_script_instance());
	
	Callable::CallError call_err;
	instance->callp(GDScriptTestRunner::test_function_name, nullptr, 0, call_err);
	
	remove_print_handler(&_print_handler);
	remove_error_handler(&_error_handler);
	
	if (call_err.error != Callable::CallError::CALL_OK) {
		enable_stdout();
		result.status = GDTEST_LOAD_ERROR;
		result.passed = false;
		ERR_FAIL_V_MSG(result, "\nCould not call test function on: '" + source_file + "'");
	}
	result.output = get_text_for_status(result.status) + "\n" + result.output;
	if (!p_is_generating) {
		result.passed = check_output(result.output);
	}
	if (obj_ref.is_null()) {
		memdelete(obj);
	}
	enable_stdout();
	GDScriptCache::remove_script(script->get_path());
	return result;
}
GDScriptTest::TestResult GDScriptTest::run_test() {