### 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)


p_source = p_function;
	}
	StringName function_name = p_function->identifier != nullptr ? p_function->identifier->name : StringName();
	if (p_function->get_datatype().is_resolving()) {
		push_error(vformat(R"(Could not resolve function "%s": Cyclic reference.)", function_name), p_source);
		return;
	}
	if (p_function->resolved_signature) {
		return;
	}
	p_function->resolved_signature = true;
#ifdef DEBUG_ENABLED
	HashSet<GDScriptWarning::Code> previously_ignored_warnings = parser->ignored_warnings;
	for (GDScriptWarning::Code ignored_warning : p_function->ignored_warnings) {
		parser->ignored_warnings.insert(ignored_warning);
	}
#endif
	GDScriptParser::FunctionNode *previous_function = parser->current_function;
	parser->current_function = p_function;
	bool previous_static_context = static_context;
	static_context = p_function->is_static;
	GDScriptParser::DataType prev_datatype = p_function->get_datatype();
	GDScriptParser::DataType resolving_datatype;
	resolving_datatype.kind = GDScriptParser::DataType::RESOLVING;
	p_function->set_datatype(resolving_datatype);
#ifdef TOOLS_ENABLED
	int default_value_count = 0;
#endif 
	for (int i = 0; i < p_function->parameters.size(); i++) {
		resolve_parameter(p_function->parameters[i]);