### 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)


StringName native_base = p_native_class;
	while (true && native_base != StringName()) {
		if (ClassDB::has_enum(native_base, p_enum_name, true)) {
			break;
		}
		native_base = ClassDB::get_parent_class_nocheck(native_base);
	}
	GDScriptParser::DataType type = make_enum_type(p_enum_name, native_base, p_meta);
	if (p_meta) {
		type.builtin_type = Variant::NIL; 
	}
	List<StringName> enum_values;
	ClassDB::get_enum_constants(native_base, p_enum_name, &enum_values, true);
	for (const StringName &E : enum_values) {
		type.enum_values[E] = ClassDB::get_integer_constant(native_base, E);
	}
	return type;
}
static GDScriptParser::DataType make_global_enum_type(const StringName &p_enum_name, const StringName &p_base, bool p_meta = true) {