### 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 (assign == "interface/editor/project_manager_screen") {
									init_screen = value;
									break;
								}
							} else if (editor) {
								if (assign == "interface/editor/editor_screen") {
									init_screen = value;
									break;
								}
							}
						}
					}
				}
			}
		}
		if (found_project && EditorPaths::get_singleton()->is_self_contained()) {
			if (ProjectSettings::get_singleton()->get_resource_path() == OS::get_singleton()->get_executable_path().get_base_dir()) {
				ERR_PRINT("You are trying to run a self-contained editor at the same location as a project. This is not allowed, since editor files will mix with project files.");
				OS::get_singleton()->set_exit_code(EXIT_FAILURE);
				return FAILED;
			}
		}
	}
#endif
	
	input = memnew(Input);
	
	{
		String display_driver = DisplayServer::get_create_function_name(display_driver_idx);
		Vector2i *window_position = nullptr;