### 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)
String warning = TTR("The resource does not have a valid path because it has not been saved.\nPlease save the scene or resource that contains this resource and try again.");
			EditorToaster::get_singleton()->popup_str(warning, EditorToaster::SEVERITY_ERROR);
			return;
		}
		String text_to_drop;
		if (drop_modifier_pressed) {
			if (resource->is_built_in()) {
				String warning = TTR("Preloading internal resources is not supported.");
				EditorToaster::get_singleton()->popup_str(warning, EditorToaster::SEVERITY_ERROR);
			} else {
				text_to_drop = _get_dropped_resource_line(resource, is_empty_line);
			}
		} else {
			text_to_drop = _quote_drop_data(path);
		}
		te->set_caret_line(row);
		te->set_caret_column(col);
		te->insert_text_at_caret(text_to_drop);
		te->grab_focus();
	}
	if (d.has("type") && (String(d["type"]) == "files" || String(d["type"]) == "files_and_dirs")) {
		te->remove_secondary_carets();
		Array files = d["files"];
		String text_to_drop;
		for (int i = 0; i < files.size(); i++) {
			const String &path = String(files[i]);
			if (drop_modifier_pressed && ResourceLoader::exists(path)) {
				Ref<Resource> resource = ResourceLoader::load(path);
				text_to_drop += _get_dropped_resource_line(resource, is_empty_line);
			} else {