### 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 (difference > 0) {
					String parent = full_path.substr(0, difference);
					int slash_idx = parent.rfind("/");
					slash_idx = parent.rfind("/", slash_idx - 1);
					parent = (slash_idx >= 0 && parent.length() > 1) ? parent.substr(slash_idx + 1) : parent;
					r_filenames.write[set_idx] = parent + r_filenames[set_idx];
				}
			}
			
			bool can_proceed = false;
			RBSet<int>::Element *E = iset.front();
			while (E) {
				String scene_name = r_filenames[E->get()];
				bool duplicate_found = false;
				for (const int &F : iset) {
					if (E->get() == F) {
						continue;
					}
					String other_scene_name = r_filenames[F];
					if (other_scene_name == scene_name) {
						duplicate_found = true;
						break;
					}
				}
				RBSet<int>::Element *to_erase = duplicate_found ? nullptr : E;