### 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)
Color clear = GLOBAL_DEF_BASIC("rendering/environment/defaults/default_clear_color", Color(0.3, 0.3, 0.3));
	RenderingServer::get_singleton()->set_default_clear_color(clear);
	if (show_logo) { 
		const bool boot_logo_image = GLOBAL_DEF_BASIC("application/boot_splash/show_image", true);
		const String boot_logo_path = String(GLOBAL_DEF_BASIC(PropertyInfo(Variant::STRING, "application/boot_splash/image", PROPERTY_HINT_FILE, "*.png"), String())).strip_edges();
		const bool boot_logo_scale = GLOBAL_DEF_BASIC("application/boot_splash/fullsize", true);
		const bool boot_logo_filter = GLOBAL_DEF_BASIC("application/boot_splash/use_filter", true);
		Ref<Image> boot_logo;
		if (boot_logo_image) {
			if (!boot_logo_path.is_empty()) {
				boot_logo.instantiate();
				Error load_err = ImageLoader::load_image(boot_logo_path, boot_logo);
				if (load_err) {
					ERR_PRINT("Non-existing or invalid boot splash at '" + boot_logo_path + "'. Loading default splash.");
				}
			}
		} else {
			
			boot_logo.instantiate();
			boot_logo->initialize_data(1, 1, false, Image::FORMAT_RGBA8);
			boot_logo->set_pixel(0, 0, Color(0, 0, 0, 0));
		}
		Color boot_bg_color = GLOBAL_GET("application/boot_splash/bg_color");
#if defined(TOOLS_ENABLED) && !defined(NO_EDITOR_SPLASH)
		boot_bg_color =
				GLOBAL_DEF_BASIC("application/boot_splash/bg_color",
						(editor || project_manager) ? boot_splash_editor_bg_color : boot_splash_bg_color);
#endif
		if (boot_logo.is_valid()) {
			RenderingServer::get_singleton()->set_boot_image(boot_logo, boot_bg_color, boot_logo_scale,