### 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)
return script;
}
void ScriptTextEditor::set_edited_resource(const Ref<Resource> &p_res) {
	ERR_FAIL_COND(script.is_valid());
	ERR_FAIL_COND(p_res.is_null());
	script = p_res;
	code_editor->get_text_editor()->set_text(script->get_source_code());
	code_editor->get_text_editor()->clear_undo_history();
	code_editor->get_text_editor()->tag_saved_version();
	emit_signal(SNAME("name_changed"));
	code_editor->update_line_and_column();
}
void ScriptTextEditor::enable_editor(Control *p_shortcut_context) {
	if (editor_enabled) {
		return;
	}
	editor_enabled = true;
	_enable_code_editor();
	_validate_script();
	if (p_shortcut_context) {
		for (int i = 0; i < edit_hb->get_child_count(); ++i) {
			Control *c = cast_to<Control>(edit_hb->get_child(i));
			if (c) {
				c->set_shortcut_context(p_shortcut_context);
			}
		}
	}
}
void ScriptTextEditor::_load_theme_settings() {