### 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)
#ifdef TESTS_ENABLED
	for (int x = 0; x < argc; x++) {
		if ((strncmp(argv[x], "--test", 6) == 0) && (strlen(argv[x]) == 6)) {
			tests_need_run = true;
			
			
			test_setup();
			int status = test_main(argc, argv);
			test_cleanup();
			return status;
		}
	}
#endif
	tests_need_run = false;
	return 0;
}
/* Engine initialization
 *
 * Consists of several methods that are called by each platform's specific main(argc, argv).
 * To fully understand engine init, one should therefore start from the platform's main and
 * see how it calls into the Main class' methods.
 *
 * The initialization is typically done in 3 steps (with the setup2 step triggered either
 * automatically by setup, or manually in the platform's main).
 *
 * - setup(execpath, argc, argv, p_second_phase) is the main entry point for all platforms,
 *   responsible for the initialization of all low level singletons and core types, and parsing
 *   command line arguments to configure things accordingly.