### 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)
_find_and_save_edited_subresources(scene, processed, flags);
	for (int i = 0; i < scene->get_child_count(); i++) {
		Node *n = scene->get_child(i);
		if (n->get_owner() != editor_data.get_edited_scene_root()) {
			continue;
		}
		_save_edited_subresources(n, processed, flags);
	}
}
void EditorNode::_find_node_types(Node *p_node, int &count_2d, int &count_3d) {
	if (p_node->is_class("Viewport") || (p_node != editor_data.get_edited_scene_root() && p_node->get_owner() != editor_data.get_edited_scene_root())) {
		return;
	}
	if (p_node->is_class("CanvasItem")) {
		count_2d++;
	} else if (p_node->is_class("Node3D")) {
		count_3d++;
	}
	for (int i = 0; i < p_node->get_child_count(); i++) {
		_find_node_types(p_node->get_child(i), count_2d, count_3d);
	}
}
void EditorNode::_save_scene_with_preview(String p_file, int p_idx) {
	EditorProgress save("save", TTR("Saving Scene"), 4);
	if (editor_data.get_edited_scene_root() != nullptr) {
		save.step(TTR("Analyzing"), 0);
		int c2d = 0;
		int c3d = 0;
		_find_node_types(editor_data.get_edited_scene_root(), c2d, c3d);
		save.step(TTR("Creating Thumbnail"), 1);