### 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 (_initializing_plugins) {
		return;
	}
	Vector<String> enabled_addons;
	for (const KeyValue<String, EditorPlugin *> &E : addon_name_to_plugin) {
		enabled_addons.push_back(E.key);
	}
	if (enabled_addons.size() == 0) {
		ProjectSettings::get_singleton()->set("editor_plugins/enabled", Variant());
	} else {
		enabled_addons.sort();
		ProjectSettings::get_singleton()->set("editor_plugins/enabled", enabled_addons);
	}
	project_settings_editor->queue_save();
}
void EditorNode::set_addon_plugin_enabled(const String &p_addon, bool p_enabled, bool p_config_changed) {
	String addon_path = p_addon;
	if (!addon_path.begins_with("res:")) {
		addon_path = "res:addons/" + addon_path + "/plugin.cfg";
	}
	ERR_FAIL_COND(p_enabled && addon_name_to_plugin.has(addon_path));
	ERR_FAIL_COND(!p_enabled && !addon_name_to_plugin.has(addon_path));
	if (!p_enabled) {
		EditorPlugin *addon = addon_name_to_plugin[addon_path];
		remove_editor_plugin(addon, p_config_changed);
		memdelete(addon);
		addon_name_to_plugin.erase(addon_path);
		_update_addon_config();
		return;