### 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 (current_enum) {
		for (int i = 0; i < current_enum->values.size(); i++) {
			const GDScriptParser::EnumNode::Value &element = current_enum->values[i];
			if (element.identifier->name == p_identifier->name) {
				StringName enum_name = current_enum->identifier ? current_enum->identifier->name : UNNAMED_ENUM;
				GDScriptParser::DataType type = make_enum_type(enum_name, parser->current_class->fqcn, false);
				if (element.parent_enum->identifier) {
					type.enum_type = element.parent_enum->identifier->name;
				}
				p_identifier->set_datatype(type);
				if (element.resolved) {
					p_identifier->is_constant = true;
					p_identifier->reduced_value = element.value;
				} else {
					push_error(R"(Cannot use another enum element before it was declared.)", p_identifier);
				}
				return; 
			}
		}
	}
	bool found_source = false;
	
	
	switch (p_identifier->source) {
		case GDScriptParser::IdentifierNode::FUNCTION_PARAMETER:
			p_identifier->set_datatype(p_identifier->parameter_source->get_datatype());
			found_source = true;
			break;
		case GDScriptParser::IdentifierNode::LOCAL_CONSTANT: