### 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)
tx->request_code_completion(true);
		} break;
		case EDIT_AUTO_INDENT: {
			String text = tx->get_text();
			Ref<Script> scr = script;
			if (scr.is_null()) {
				return;
			}
			tx->begin_complex_operation();
			int begin, end;
			if (tx->has_selection()) {
				begin = tx->get_selection_from_line();
				end = tx->get_selection_to_line();
				
				if (tx->get_selection_to_column() == 0) {
					end--;
				}
			} else {
				begin = 0;
				end = tx->get_line_count() - 1;
			}
			scr->get_language()->auto_indent_code(text, begin, end);
			Vector<String> lines = text.split("\n");
			for (int i = begin; i <= end; ++i) {
				tx->set_line(i, lines[i]);
			}
			tx->end_complex_operation();
		} break;
		case EDIT_TRIM_TRAILING_WHITESAPCE: {
			trim_trailing_whitespace();