### 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)
errors_panel->set_h_size_flags(SIZE_EXPAND_FILL);
	errors_panel->set_meta_underline(true);
	errors_panel->set_selection_enabled(true);
	errors_panel->set_context_menu_enabled(true);
	errors_panel->set_focus_mode(FOCUS_CLICK);
	errors_panel->hide();
	update_settings();
	code_editor->get_text_editor()->set_code_hint_draw_below(EDITOR_GET("text_editor/completion/put_callhint_tooltip_below_current_line"));
	code_editor->get_text_editor()->set_symbol_lookup_on_click_enabled(true);
	code_editor->get_text_editor()->set_context_menu_enabled(false);
	context_menu = memnew(PopupMenu);
	color_panel = memnew(PopupPanel);
	edit_hb = memnew(HBoxContainer);
	edit_menu = memnew(MenuButton);
	edit_menu->set_text(TTR("Edit"));
	edit_menu->set_switch_on_hover(true);
	edit_menu->set_shortcut_context(this);
	highlighter_menu = memnew(PopupMenu);
	highlighter_menu->set_name("HighlighterMenu");
	Ref<EditorPlainTextSyntaxHighlighter> plain_highlighter;
	plain_highlighter.instantiate();
	add_syntax_highlighter(plain_highlighter);
	Ref<EditorStandardSyntaxHighlighter> highlighter;
	highlighter.instantiate();
	add_syntax_highlighter(highlighter);
	set_syntax_highlighter(highlighter);
	search_menu = memnew(MenuButton);
	search_menu->set_text(TTR("Search"));
	search_menu->set_switch_on_hover(true);
	search_menu->set_shortcut_context(this);