### 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)


ERR_FAIL_COND_V(!Variant::has_utility_function(p_function), MethodInfo());
	MethodInfo info(p_function);
	if (Variant::has_utility_function_return_value(p_function)) {
		info.return_val.type = Variant::get_utility_function_return_type(p_function);
		if (info.return_val.type == Variant::NIL) {
			info.return_val.usage |= PROPERTY_USAGE_NIL_IS_VARIANT;
		}
	}
	if (Variant::is_utility_function_vararg(p_function)) {
		info.flags |= METHOD_FLAG_VARARG;
	} else {
		for (int i = 0; i < Variant::get_utility_function_argument_count(p_function); i++) {
			PropertyInfo pi;
#ifdef DEBUG_METHODS_ENABLED
			pi.name = Variant::get_utility_function_argument_name(p_function, i);
#else
			pi.name = "arg" + itos(i + 1);
#endif
			pi.type = Variant::get_utility_function_argument_type(p_function, i);
			info.arguments.push_back(pi);
		}
	}
	return info;
}
static GDScriptParser::DataType make_callable_type(const MethodInfo &p_info) {