### 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)
} break;
		case EDIT_SELECT_ALL: {
			tx->select_all();
			tx->call_deferred(SNAME("grab_focus"));
		} break;
		case EDIT_MOVE_LINE_UP: {
			code_editor->move_lines_up();
		} break;
		case EDIT_MOVE_LINE_DOWN: {
			code_editor->move_lines_down();
		} break;
		case EDIT_INDENT: {
			Ref<Script> scr = script;
			if (scr.is_null()) {
				return;
			}
			tx->indent_lines();
		} break;
		case EDIT_UNINDENT: {
			Ref<Script> scr = script;
			if (scr.is_null()) {
				return;
			}
			tx->unindent_lines();
		} break;
		case EDIT_DELETE_LINE: {
			code_editor->delete_lines();
		} break;
		case EDIT_DUPLICATE_SELECTION: {
			code_editor->duplicate_selection();