### 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 (!argument->is_constant) {
			push_error(vformat(R"(Argument %d of annotation "%s" isn't a constant expression.)", i + 1, p_annotation->name), argument);
			return;
		}
		Variant value = argument->reduced_value;
		if (value.get_type() != argument_info.type) {
#ifdef DEBUG_ENABLED
			if (argument_info.type == Variant::INT && value.get_type() == Variant::FLOAT) {
				parser->push_warning(argument, GDScriptWarning::NARROWING_CONVERSION);
			}
#endif
			if (!Variant::can_convert_strict(value.get_type(), argument_info.type)) {
				push_error(vformat(R"(Invalid argument for annotation "%s": argument %d should be "%s" but is "%s".)", p_annotation->name, i + 1, Variant::get_type_name(argument_info.type), argument->get_datatype().to_string()), argument);
				return;
			}
			Variant converted_to;
			const Variant *converted_from = &value;
			Callable::CallError call_error;
			Variant::construct(argument_info.type, converted_to, &converted_from, 1, call_error);
			if (call_error.error != Callable::CallError::CALL_OK) {
				push_error(vformat(R"(Cannot convert argument %d of annotation "%s" from "%s" to "%s".)", i + 1, p_annotation->name, Variant::get_type_name(value.get_type()), Variant::get_type_name(argument_info.type)), argument);
				return;
			}
			value = converted_to;
		}
		p_annotation->resolved_arguments.push_back(value);
	}
}
void GDScriptAnalyzer::resolve_function_signature(GDScriptParser::FunctionNode *p_function, const GDScriptParser::Node *p_source, bool p_is_lambda) {
	if (p_source == nullptr) {