### 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 (autoload_cache.size() <= 1) {
		return false;
	}
	PackedStringArray autoloads;
	TreeItem *next = tree->get_next_selected(nullptr);
	while (next) {
		autoloads.push_back(next->get_text(0));
		next = tree->get_next_selected(next);
	}
	if (autoloads.size() == 0 || autoloads.size() == autoload_cache.size()) {
		return Variant();
	}
	VBoxContainer *preview = memnew(VBoxContainer);
	int max_size = MIN(PREVIEW_LIST_MAX_SIZE, autoloads.size());
	for (int i = 0; i < max_size; i++) {
		Label *label = memnew(Label(autoloads[i]));
		label->set_self_modulate(Color(1, 1, 1, Math::lerp(1, 0, float(i) / PREVIEW_LIST_MAX_SIZE)));
		preview->add_child(label);
	}
	tree->set_drop_mode_flags(Tree::DROP_MODE_INBETWEEN);
	tree->set_drag_preview(preview);
	Dictionary drop_data;
	drop_data["type"] = "autoload";
	drop_data["autoloads"] = autoloads;
	return drop_data;
}
bool EditorAutoloadSettings::can_drop_data_fw(const Point2 &p_point, const Variant &p_data, Control *p_control) const {