### 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)


p_base_type.is_meta_type = false;
		} else {
			push_error("Cannot call function on enum value.", p_source);
			return false;
		}
	}
	if (p_base_type.kind == GDScriptParser::DataType::BUILTIN) {
		
		Callable::CallError err;
		Variant dummy;
		Variant::construct(p_base_type.builtin_type, dummy, nullptr, 0, err);
		if (err.error != Callable::CallError::CALL_OK) {
			ERR_FAIL_V_MSG(false, "Could not construct base Variant type.");
		}
		List<MethodInfo> methods;
		dummy.get_method_list(&methods);
		for (const MethodInfo &E : methods) {
			if (E.name == p_function) {
				function_signature_from_info(E, r_return_type, r_par_types, r_default_arg_count, r_method_flags);
				
				if (!r_method_flags.has_flag(METHOD_FLAG_STATIC) && was_enum && !(E.flags & METHOD_FLAG_CONST)) {
					push_error(vformat(R"*(Cannot call non-const Dictionary function "%s()" on enum "%s".)*", p_function, p_base_type.enum_type), p_source);
				}
				return true;
			}
		}
		return false;
	}
	StringName base_native = p_base_type.native_type;
	if (base_native != StringName()) {