A subclass of an GDExtension subclass of EditorPlugin still cannot be used as an editor plugin

[andreymal]

Tested versions

4.2.1.rc1

System information

Linux

Issue description

This is a direct continuation of #85268, see that issue for context.

Although #85268 is technically fixed, something else prevents such inheritance from being implemented:

class MyEditorPluginBase : public EditorPlugin {
    GDCLASS(MyEditorPluginBase, EditorPlugin)
// ...
};

@tool
class_name MyEditorPlugin
extends MyEditorPluginBase

When trying to use this class as an editor plugin, Godot prints an error:

ERROR: Script inherits from native type 'MyEditorPluginBase', so it can't be assigned to an object of type 'EditorPlugin'.
   at: instance_create (modules/gdscript/gdscript.cpp:390)

Steps to reproduce

1. Make a GDExtension subclass of EditorPlugin (the programming language used doesn't matter)
2. Make a GDScript subclass of that GDExtension class
3. Try to use it as an editor plugin (create plugin.cfg, enable it in the project settings)

Minimal reproduction project (MRP)

As requested by @YuriSizov, I made a godot-cpp example to make it easier to reproduce this issue (but note that I'm not a C++ developer and blindly copied code from the documentation):

NativeEditorPluginTest.zip

See also #85268 for a godot-rust example

[Lord-of-Madness]

Same with subclasses for EditorScript. Same bug same steps to reproduce