### 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)


return bad_type;
		}
		result.kind = GDScriptParser::DataType::BUILTIN;
		result.builtin_type = GDScriptParser::get_builtin_type(first);
		if (result.builtin_type == Variant::ARRAY) {
			GDScriptParser::DataType container_type = type_from_metatype(resolve_datatype(p_type->container_type));
			if (container_type.kind != GDScriptParser::DataType::VARIANT) {
				container_type.is_constant = false;
				result.set_container_element_type(container_type);
			}
		}
	} else if (class_exists(first)) {
		
		result.kind = GDScriptParser::DataType::NATIVE;
		result.builtin_type = Variant::OBJECT;
		result.native_type = first;
	} else if (ScriptServer::is_global_class(first)) {
		if (parser->script_path == ScriptServer::get_global_class_path(first)) {
			result = parser->head->get_datatype();
		} else {
			String path = ScriptServer::get_global_class_path(first);
			String ext = path.get_extension();
			if (ext == GDScriptLanguage::get_singleton()->get_extension()) {
				Ref<GDScriptParserRef> ref = get_parser_for(path);
				if (!ref.is_valid() || ref->raise_status(GDScriptParserRef::INHERITANCE_SOLVED) != OK) {
					push_error(vformat(R"(Could not parse global class "%s" from "%s".)", first, ScriptServer::get_global_class_path(first)), p_type);
					return bad_type;
				}
				result = ref->get_parser()->head->get_datatype();
			} else {