### 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;
	type.type_source = GDScriptParser::DataType::ANNOTATED_EXPLICIT;
	type.kind = GDScriptParser::DataType::SCRIPT;
	type.builtin_type = Variant::OBJECT;
	type.native_type = p_script->get_instance_base_type();
	type.script_type = p_script;
	type.script_path = p_script->get_path();
	type.is_constant = true;
	type.is_meta_type = true;
	return type;
}
static GDScriptParser::DataType make_enum_type(const StringName &p_enum_name, const String &p_base_name, const bool p_meta = false) {
	GDScriptParser::DataType type;
	type.type_source = GDScriptParser::DataType::ANNOTATED_EXPLICIT;
	type.kind = GDScriptParser::DataType::ENUM;
	type.builtin_type = p_meta ? Variant::DICTIONARY : Variant::INT;
	type.enum_type = p_enum_name;
	type.is_constant = true;
	type.is_meta_type = p_meta;
	
	
	if (p_base_name.is_empty()) {
		type.native_type = p_enum_name;
	} else {
		type.native_type = p_base_name + ENUM_SEPARATOR + p_enum_name;
	}
	return type;
}
static GDScriptParser::DataType make_native_enum_type(const StringName &p_enum_name, const StringName &p_native_class, bool p_meta = true) {