### 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)
p_layout->set_value(p_section, config_key, names);
		}
		int selected_tab_idx = dock_slot[i]->get_current_tab();
		if (selected_tab_idx >= 0) {
			p_layout->set_value(p_section, "dock_" + itos(i + 1) + "_selected_tab_idx", selected_tab_idx);
		}
	}
	Dictionary floating_docks_dump;
	for (WindowWrapper *wrapper : floating_docks) {
		Control *dock = wrapper->get_wrapped_control();
		Dictionary dock_dump;
		dock_dump["window_rect"] = wrapper->get_window_rect();
		int screen = wrapper->get_window_screen();
		dock_dump["window_screen"] = wrapper->get_window_screen();
		dock_dump["window_screen_rect"] = DisplayServer::get_singleton()->screen_get_usable_rect(screen);
		String name = dock->get_name();
		floating_docks_dump[name] = dock_dump;
		int dock_slot_id = wrapper->get_meta("dock_slot");
		String config_key = "dock_" + itos(dock_slot_id + 1);
		String names = p_layout->get_value(p_section, config_key, "");
		if (names.is_empty()) {
			names = name;
		} else {
			names += "," + name;
		}
		p_layout->set_value(p_section, config_key, names);
	}
	p_layout->set_value(p_section, "dock_floating", floating_docks_dump);
	for (int i = 0; i < vsplits.size(); i++) {
		if (vsplits[i]->is_visible_in_tree()) {