### 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)


if (p_source == nullptr && parser->has_class(p_class)) {
		p_source = p_class;
	}
	if (p_class->resolved_body) {
		return;
	}
	if (!parser->has_class(p_class)) {
		String script_path = p_class->get_datatype().script_path;
		Ref<GDScriptParserRef> parser_ref = get_parser_for(script_path);
		if (parser_ref.is_null()) {
			push_error(vformat(R"(Could not find script "%s".)", script_path), p_source);
			return;
		}
		Error err = parser_ref->raise_status(GDScriptParserRef::PARSED);
		if (err) {
			push_error(vformat(R"(Could not resolve script "%s": %s.)", script_path, error_names[err]), p_source);
			return;
		}
		ERR_FAIL_COND_MSG(!parser_ref->get_parser()->has_class(p_class), R"(Parser bug: Mismatched external parser.)");
		GDScriptAnalyzer *other_analyzer = parser_ref->get_analyzer();
		GDScriptParser *other_parser = parser_ref->get_parser();
		int error_count = other_parser->errors.size();
		other_analyzer->resolve_class_body(p_class);
		if (other_parser->errors.size() > error_count) {
			push_error(vformat(R"(Could not resolve class "%s".)", p_class->fqcn), p_source);