### 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)
"normal_font", EditorNode::get_singleton()->get_editor_theme()->get_font(SNAME("main"), EditorStringName(EditorFonts)));
	warnings_panel->add_theme_font_size_override(
			"normal_font_size", EditorNode::get_singleton()->get_editor_theme()->get_font_size(SNAME("main_size"), EditorStringName(EditorFonts)));
	warnings_panel->connect("meta_clicked", callable_mp(this, &ScriptTextEditor::_warning_clicked));
	editor_box->add_child(errors_panel);
	errors_panel->add_theme_font_override(
			"normal_font", EditorNode::get_singleton()->get_editor_theme()->get_font(SNAME("main"), EditorStringName(EditorFonts)));
	errors_panel->add_theme_font_size_override(
			"normal_font_size", EditorNode::get_singleton()->get_editor_theme()->get_font_size(SNAME("main_size"), EditorStringName(EditorFonts)));
	errors_panel->connect("meta_clicked", callable_mp(this, &ScriptTextEditor::_error_clicked));
	add_child(context_menu);
	context_menu->connect("id_pressed", callable_mp(this, &ScriptTextEditor::_edit_option));
	add_child(color_panel);
	color_picker = memnew(ColorPicker);
	color_picker->set_deferred_mode(true);
	color_picker->connect("color_changed", callable_mp(this, &ScriptTextEditor::_color_changed));
	color_panel->connect("about_to_popup", callable_mp(EditorNode::get_singleton(), &EditorNode::setup_color_picker).bind(color_picker));
	color_panel->add_child(color_picker);
	quick_open = memnew(ScriptEditorQuickOpen);
	quick_open->connect("goto_line", callable_mp(this, &ScriptTextEditor::_goto_line));
	add_child(quick_open);
	goto_line_dialog = memnew(GotoLineDialog);
	add_child(goto_line_dialog);
	add_child(connection_info_dialog);
	edit_hb->add_child(edit_menu);
	edit_menu->connect("about_to_popup", callable_mp(this, &ScriptTextEditor::_prepare_edit_menu));
	edit_menu->get_popup()->add_shortcut(ED_GET_SHORTCUT("ui_undo"), EDIT_UNDO);
	edit_menu->get_popup()->add_shortcut(ED_GET_SHORTCUT("ui_redo"), EDIT_REDO);
	edit_menu->get_popup()->add_separator();
	edit_menu->get_popup()->add_shortcut(ED_GET_SHORTCUT("ui_cut"), EDIT_CUT);