### 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)
if (!init_use_custom_screen && (editor || project_manager) && EditorPaths::get_singleton()->are_paths_valid()) {
			Ref<DirAccess> dir = DirAccess::open(EditorPaths::get_singleton()->get_config_dir());
			ERR_FAIL_COND_V(dir.is_null(), FAILED);
			String config_file_name = "editor_settings-" + itos(VERSION_MAJOR) + ".tres";
			String config_file_path = EditorPaths::get_singleton()->get_config_dir().path_join(config_file_name);
			if (dir->file_exists(config_file_name)) {
				Error err;
				Ref<FileAccess> f = FileAccess::open(config_file_path, FileAccess::READ, &err);
				if (f.is_valid()) {
					VariantParser::StreamFile stream;
					stream.f = f;
					String assign;
					Variant value;
					VariantParser::Tag next_tag;
					int lines = 0;
					String error_text;
					VariantParser::ResourceParser rp_new;
					rp_new.ext_func = _parse_resource_dummy;
					rp_new.sub_func = _parse_resource_dummy;
					while (true) {
						assign = Variant();
						next_tag.fields.clear();
						next_tag.name = String();
						err = VariantParser::parse_tag_assign_eof(&stream, lines, error_text, next_tag, assign, value, &rp_new, true);
						if (err == ERR_FILE_EOF) {
							break;
						}
						if (err == OK && !assign.is_empty()) {
							if (project_manager) {