### 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)
gui_base->add_child(install_android_build_template);
	remove_android_build_template = memnew(ConfirmationDialog);
	remove_android_build_template->set_text(TTR("The Android build template is already installed in this project and it won't be overwritten.\nRemove the \"res:android/build\" directory manually before attempting this operation again."));
	remove_android_build_template->set_ok_button_text(TTR("Show in File Manager"));
	remove_android_build_template->connect("confirmed", callable_mp(this, &EditorNode::_menu_option).bind(FILE_EXPLORE_ANDROID_BUILD_TEMPLATES));
	gui_base->add_child(remove_android_build_template);
	file_templates = memnew(EditorFileDialog);
	file_templates->set_title(TTR("Import Templates From ZIP File"));
	gui_base->add_child(file_templates);
	file_templates->set_file_mode(EditorFileDialog::FILE_MODE_OPEN_FILE);
	file_templates->set_access(EditorFileDialog::ACCESS_FILESYSTEM);
	file_templates->clear_filters();
	file_templates->add_filter("*.tpz", TTR("Template Package"));
	file = memnew(EditorFileDialog);
	gui_base->add_child(file);
	file->set_current_dir("res:");
	file_export_lib = memnew(EditorFileDialog);
	file_export_lib->set_title(TTR("Export Library"));
	file_export_lib->set_file_mode(EditorFileDialog::FILE_MODE_SAVE_FILE);
	file_export_lib->connect("file_selected", callable_mp(this, &EditorNode::_dialog_action));
	file_export_lib_merge = memnew(CheckBox);
	file_export_lib_merge->set_text(TTR("Merge With Existing"));
	file_export_lib_merge->set_h_size_flags(Control::SIZE_SHRINK_CENTER);
	file_export_lib_merge->set_pressed(true);
	file_export_lib->get_vbox()->add_child(file_export_lib_merge);
	file_export_lib_apply_xforms = memnew(CheckBox);
	file_export_lib_apply_xforms->set_text(TTR("Apply MeshInstance Transforms"));
	file_export_lib_apply_xforms->set_h_size_flags(Control::SIZE_SHRINK_CENTER);
	file_export_lib_apply_xforms->set_pressed(false);
	file_export_lib->get_vbox()->add_child(file_export_lib_apply_xforms);