### 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 (source == nullptr) {
		return;
	}
	GDScriptParser::DataType datatype;
	datatype.kind = GDScriptParser::DataType::VARIANT;
	source->set_datatype(datatype);
}
void GDScriptAnalyzer::mark_lambda_use_self() {
	for (GDScriptParser::LambdaNode *lambda : lambda_stack) {
		lambda->use_self = true;
	}
}
bool GDScriptAnalyzer::class_exists(const StringName &p_class) const {
	return ClassDB::class_exists(p_class) && ClassDB::is_class_exposed(p_class);
}
Ref<GDScriptParserRef> GDScriptAnalyzer::get_parser_for(const String &p_path) {
	Ref<GDScriptParserRef> ref;
	if (depended_parsers.has(p_path)) {
		ref = depended_parsers[p_path];
	} else {
		Error err = OK;
		ref = GDScriptCache::get_parser(p_path, GDScriptParserRef::EMPTY, err, parser->script_path);
		if (ref.is_valid()) {
			depended_parsers[p_path] = ref;
		}
	}
	return ref;
}
Error GDScriptAnalyzer::resolve_inheritance() {