### 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)
double process_step = advance.process_step;
	double scaled_step = process_step * time_scale;
	Engine::get_singleton()->_process_step = process_step;
	Engine::get_singleton()->_physics_interpolation_fraction = advance.interpolation_fraction;
	uint64_t physics_process_ticks = 0;
	uint64_t process_ticks = 0;
	uint64_t navigation_process_ticks = 0;
	frame += ticks_elapsed;
	last_ticks = ticks;
	const int max_physics_steps = Engine::get_singleton()->get_max_physics_steps_per_frame();
	if (fixed_fps == -1 && advance.physics_steps > max_physics_steps) {
		process_step -= (advance.physics_steps - max_physics_steps) * physics_step;
		advance.physics_steps = max_physics_steps;
	}
	bool exit = false;
	/
	XRServer::get_singleton()->_process();
	NavigationServer2D::get_singleton()->sync();
	NavigationServer3D::get_singleton()->sync();
	for (int iters = 0; iters < advance.physics_steps; ++iters) {
		if (Input::get_singleton()->is_using_input_buffering() && agile_input_event_flushing) {
			Input::get_singleton()->flush_buffered_events();
		}
		Engine::get_singleton()->_in_physics = true;
		uint64_t physics_begin = OS::get_singleton()->get_ticks_usec();
		PhysicsServer3D::get_singleton()->sync();
		PhysicsServer3D::get_singleton()->flush_queries();
		PhysicsServer2D::get_singleton()->sync();
		PhysicsServer2D::get_singleton()->flush_queries();
		if (OS::get_singleton()->get_main_loop()->physics_process(physics_step * time_scale)) {