### 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)
dock_float->connect("pressed", callable_mp(this, &EditorNode::_dock_make_selected_float));
		dock_vb->add_child(dock_float);
	}
	dock_select_popup->reset_size();
	for (int i = 0; i < DOCK_SLOT_MAX; i++) {
		dock_slot[i]->set_custom_minimum_size(Size2(170, 0) * EDSCALE);
		dock_slot[i]->set_v_size_flags(Control::SIZE_EXPAND_FILL);
		dock_slot[i]->set_popup(dock_select_popup);
		dock_slot[i]->connect("pre_popup_pressed", callable_mp(this, &EditorNode::_dock_pre_popup).bind(i));
		dock_slot[i]->set_drag_to_rearrange_enabled(true);
		dock_slot[i]->set_tabs_rearrange_group(1);
		dock_slot[i]->connect("tab_changed", callable_mp(this, &EditorNode::_dock_tab_changed));
		dock_slot[i]->set_use_hidden_tabs_for_min_size(true);
	}
	editor_layout_save_delay_timer = memnew(Timer);
	add_child(editor_layout_save_delay_timer);
	editor_layout_save_delay_timer->set_wait_time(0.5);
	editor_layout_save_delay_timer->set_one_shot(true);
	editor_layout_save_delay_timer->connect("timeout", callable_mp(this, &EditorNode::_save_editor_layout));
	top_split = memnew(VSplitContainer);
	center_split->add_child(top_split);
	top_split->set_v_size_flags(Control::SIZE_EXPAND_FILL);
	top_split->set_collapsed(true);
	VBoxContainer *srt = memnew(VBoxContainer);
	srt->set_v_size_flags(Control::SIZE_EXPAND_FILL);
	srt->add_theme_constant_override("separation", 0);
	top_split->add_child(srt);
	scene_tabs = memnew(EditorSceneTabs);
	srt->add_child(scene_tabs);
	scene_tabs->connect("tab_changed", callable_mp(this, &EditorNode::_set_current_scene));