### Godot version

4.1.beta3

### System information

Fedora Workstation 38 - Godot 4.1.beta3 - Vulkan (Forward+)

### Issue description

**This is an issue created by the production team, we're working on it**

Currently, it's impossible to call virtual functions within GDScript.

This currently returns an error:
```gdscript
# a.gd
extends Node

func _process(delta: float) -> void:
	pass
```

```gdscript
# main.gd
extends Node

var my_node: Node = preload("res://a.gd").new()

func _process(delta: float) -> void:
	my_node._process(delta)  # Cannot call virtual function "_process()" because it hasn't been defined.
```

### Steps to reproduce

1. Create a script (`a.gd`) based on `Node` that declares `_process()`;
2. Create a main node;
3. Attach a script to the main node;
4. Initialize a variable with a new `a.gd` instance;
5. Try to run `_process()` on that node;
6. Find out that it returns an error.

### Minimal reproduction project

[virtual_functions.zip (updated)](https://github.com/godotengine/godot/files/11823992/virtual_functions.zip)


result = make_script_meta_type(ResourceLoader::load(path, "Script"));
			}
		}
	} else if (ProjectSettings::get_singleton()->has_autoload(first) && ProjectSettings::get_singleton()->get_autoload(first).is_singleton) {
		const ProjectSettings::AutoloadInfo &autoload = ProjectSettings::get_singleton()->get_autoload(first);
		Ref<GDScriptParserRef> ref = get_parser_for(autoload.path);
		if (ref.is_null()) {
			push_error(vformat(R"(The referenced autoload "%s" (from "%s") could not be loaded.)", first, autoload.path), p_type);
			return bad_type;
		}
		if (ref->raise_status(GDScriptParserRef::INHERITANCE_SOLVED) != OK) {
			push_error(vformat(R"(Could not parse singleton "%s" from "%s".)", first, autoload.path), p_type);
			return bad_type;
		}
		result = ref->get_parser()->head->get_datatype();
	} else if (ClassDB::has_enum(parser->current_class->base_type.native_type, first)) {
		
		result = make_native_enum_type(first, parser->current_class->base_type.native_type);
	} else if (CoreConstants::is_global_enum(first)) {
		if (p_type->type_chain.size() > 1) {
			push_error(R"(Enums cannot contain nested types.)", p_type->type_chain[1]);
			return bad_type;
		}
		result = make_global_enum_type(first, StringName());
	} else {
		
		List<GDScriptParser::ClassNode *> script_classes;
		bool found = false;
		get_class_node_current_scope_classes(parser->current_class, &script_classes);
		for (GDScriptParser::ClassNode *script_class : script_classes) {