### 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)
bool is_node = current_obj->is_class("Node");
	bool stay_in_script_editor_on_node_selected = bool(EDITOR_GET("text_editor/behavior/navigation/stay_in_script_editor_on_node_selected"));
	bool skip_main_plugin = false;
	String editable_info; 
	bool info_is_warning = false;
	if (current_obj->has_method("_is_read_only")) {
		if (current_obj->call("_is_read_only")) {
			editable_info = TTR("This object is marked as read-only, so it's not editable.");
		}
	}
	if (is_resource) {
		Resource *current_res = Object::cast_to<Resource>(current_obj);
		ERR_FAIL_NULL(current_res);
		InspectorDock::get_inspector_singleton()->edit(current_res);
		SceneTreeDock::get_singleton()->set_selected(nullptr);
		NodeDock::get_singleton()->set_node(nullptr);
		InspectorDock::get_singleton()->update(nullptr);
		ImportDock::get_singleton()->set_edit_path(current_res->get_path());
		int subr_idx = current_res->get_path().find("::");
		if (subr_idx != -1) {
			String base_path = current_res->get_path().substr(0, subr_idx);
			if (FileAccess::exists(base_path + ".import")) {
				if (!base_path.is_resource_file()) {
					if (get_edited_scene() && get_edited_scene()->get_scene_file_path() == base_path) {
						info_is_warning = true;
					}
				}
				editable_info = TTR("This resource belongs to a scene that was imported, so it's not editable.\nPlease read the documentation relevant to importing scenes to better understand this workflow.");
			} else if ((!get_edited_scene() || get_edited_scene()->get_scene_file_path() != base_path) && ResourceLoader::get_resource_type(base_path) == "PackedScene") {
				editable_info = TTR("This resource belongs to a scene that was instantiated or inherited.\nChanges to it must be made inside the original scene.");