### 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)
Ref<Image> img;
		
		
		
		if (c3d == 0 && c2d == 0) {
			img.instantiate();
			img->initialize_data(1, 1, false, Image::FORMAT_RGB8);
		} else if (c3d < c2d) {
			Ref<ViewportTexture> viewport_texture = scene_root->get_texture();
			if (viewport_texture->get_width() > 0 && viewport_texture->get_height() > 0) {
				img = viewport_texture->get_image();
			}
		} else {
			
			
			
			Ref<EditorFeatureProfile> profile = feature_profile_manager->get_current_profile();
			if (!profile.is_valid() || !profile->is_feature_disabled(EditorFeatureProfile::FEATURE_3D)) {
				img = Node3DEditor::get_singleton()->get_editor_viewport(0)->get_viewport_node()->get_texture()->get_image();
			}
		}
		if (img.is_valid() && img->get_width() > 0 && img->get_height() > 0) {
			img = img->duplicate();
			save.step(TTR("Creating Thumbnail"), 2);
			save.step(TTR("Creating Thumbnail"), 3);
			int preview_size = EDITOR_GET("filesystem/file_dialog/thumbnail_size");
			preview_size *= EDSCALE;
			
			int vp_size = MIN(img->get_width(), img->get_height());