### 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)


GDScriptParser::DataType type = make_enum_type(p_enum_name, p_base, p_meta);
	if (p_meta) {
		type.builtin_type = Variant::NIL; 
		type.is_pseudo_type = true;
	}
	HashMap<StringName, int64_t> enum_values;
	CoreConstants::get_enum_values(type.native_type, &enum_values);
	for (const KeyValue<StringName, int64_t> &element : enum_values) {
		type.enum_values[element.key] = element.value;
	}
	return type;
}
static GDScriptParser::DataType make_builtin_meta_type(Variant::Type p_type) {