### 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)
_screenshot();
}
void EditorNode::_screenshot(bool p_use_utc) {
	String name = "editor_screenshot_" + Time::get_singleton()->get_datetime_string_from_system(p_use_utc).replace(":", "") + ".png";
	NodePath path = String("user:") + name;
	_save_screenshot(path);
	if (EDITOR_GET("interface/editor/automatically_open_screenshots")) {
		OS::get_singleton()->shell_show_in_file_manager(ProjectSettings::get_singleton()->globalize_path(path), true);
	}
}
void EditorNode::_save_screenshot(NodePath p_path) {
	Control *editor_main_screen = EditorInterface::get_singleton()->get_editor_main_screen();
	ERR_FAIL_NULL_MSG(editor_main_screen, "Cannot get the editor main screen control.");
	Viewport *viewport = editor_main_screen->get_viewport();
	ERR_FAIL_NULL_MSG(viewport, "Cannot get a viewport from the editor main screen.");
	Ref<ViewportTexture> texture = viewport->get_texture();
	ERR_FAIL_COND_MSG(texture.is_null(), "Cannot get a viewport texture from the editor main screen.");
	Ref<Image> img = texture->get_image();
	ERR_FAIL_COND_MSG(img.is_null(), "Cannot get an image from a viewport texture of the editor main screen.");
	Error error = img->save_png(p_path);
	ERR_FAIL_COND_MSG(error != OK, "Cannot save screenshot to file '" + p_path + "'.");
}
void EditorNode::_tool_menu_option(int p_idx) {