### 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)
add_child(error_message);
	Label *l = memnew(Label);
	l->set_text(TTR("Path:"));
	hbc->add_child(l);
	autoload_add_path = memnew(LineEdit);
	hbc->add_child(autoload_add_path);
	autoload_add_path->set_h_size_flags(Control::SIZE_EXPAND_FILL);
	autoload_add_path->set_clear_button_enabled(true);
	autoload_add_path->set_placeholder(vformat(TTR("Set path or press \"%s\" to create a script."), TTR("Add")));
	autoload_add_path->connect("text_changed", callable_mp(this, &EditorAutoloadSettings::_autoload_path_text_changed));
	browse_button = memnew(Button);
	hbc->add_child(browse_button);
	browse_button->connect("pressed", callable_mp(this, &EditorAutoloadSettings::_browse_autoload_add_path));
	file_dialog = memnew(EditorFileDialog);
	hbc->add_child(file_dialog);
	file_dialog->connect("file_selected", callable_mp(this, &EditorAutoloadSettings::_set_autoload_add_path));
	file_dialog->connect("dir_selected", callable_mp(this, &EditorAutoloadSettings::_set_autoload_add_path));
	file_dialog->connect("files_selected", callable_mp(this, &EditorAutoloadSettings::_set_autoload_add_path));
	hbc->set_h_size_flags(SIZE_EXPAND_FILL);
	file_dialog->set_file_mode(EditorFileDialog::FILE_MODE_OPEN_FILE);
	file_dialog->connect("file_selected", callable_mp(this, &EditorAutoloadSettings::_autoload_file_callback));
	l = memnew(Label);
	l->set_text(TTR("Node Name:"));
	hbc->add_child(l);
	autoload_add_name = memnew(LineEdit);
	autoload_add_name->set_h_size_flags(SIZE_EXPAND_FILL);
	autoload_add_name->connect("text_submitted", callable_mp(this, &EditorAutoloadSettings::_autoload_text_submitted));
	autoload_add_name->connect("text_changed", callable_mp(this, &EditorAutoloadSettings::_autoload_text_changed));
	hbc->add_child(autoload_add_name);
	add_autoload = memnew(Button);