### 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)
doc_data_classes[name] = path;
			if (!checked_paths.has(path)) {
				checked_paths.insert(path);
				/
				Ref<DirAccess> da = DirAccess::create_for_path(path);
				err = da->make_dir_recursive(path);
				ERR_FAIL_COND_V_MSG(err != OK, false, "Error: Can't create directory: " + path + ": " + itos(err));
				print_line("Loading docs from: " + path);
				err = docsrc.load_classes(path);
				ERR_FAIL_COND_V_MSG(err != OK, false, "Error loading docs from: " + path + ": " + itos(err));
			}
		}
		String index_path = doc_tool_path.path_join("doc/classes");
		/
		Ref<DirAccess> da = DirAccess::create_for_path(index_path);
		err = da->make_dir_recursive(index_path);
		ERR_FAIL_COND_V_MSG(err != OK, false, "Error: Can't create index directory: " + index_path + ": " + itos(err));
		print_line("Loading classes from: " + index_path);
		err = docsrc.load_classes(index_path);
		ERR_FAIL_COND_V_MSG(err != OK, false, "Error loading classes from: " + index_path + ": " + itos(err));
		checked_paths.insert(index_path);
		print_line("Merging docs...");
		doc.merge_from(docsrc);
		for (const String &E : checked_paths) {
			print_line("Erasing old docs at: " + E);
			err = DocTools::erase_classes(E);
			ERR_FAIL_COND_V_MSG(err != OK, false, "Error erasing old docs at: " + E + ": " + itos(err));
		}
		print_line("Generating new docs...");
		err = doc.save_classes(index_path, doc_data_classes);