### 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)


case GDScriptParser::DataType::VARIANT:
		case GDScriptParser::DataType::BUILTIN:
		case GDScriptParser::DataType::ENUM:
		case GDScriptParser::DataType::RESOLVING:
		case GDScriptParser::DataType::UNRESOLVED:
			break; 
	}
	switch (p_target.kind) {
		case GDScriptParser::DataType::NATIVE: {
			if (p_target.is_meta_type) {
				return ClassDB::is_parent_class(src_native, GDScriptNativeClass::get_class_static());
			}
			return ClassDB::is_parent_class(src_native, p_target.native_type);
		}
		case GDScriptParser::DataType::SCRIPT:
			if (p_target.is_meta_type) {
				return ClassDB::is_parent_class(src_native, p_target.script_type->get_class_name());
			}
			while (src_script.is_valid()) {
				if (src_script == p_target.script_type) {
					return true;
				}
				src_script = src_script->get_base_script();
			}
			return false;
		case GDScriptParser::DataType::CLASS:
			if (p_target.is_meta_type) {
				return ClassDB::is_parent_class(src_native, GDScript::get_class_static());
			}
			while (src_class != nullptr) {