### 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)


#else
				push_error(vformat(R"(Cannot find constant "%s" on base "%s".)", name, base.to_string()), p_identifier);
#endif 
			}
		} else {
			switch (base.builtin_type) {
				case Variant::NIL: {
					if (base.is_hard_type()) {
						push_error(vformat(R"(Invalid get index "%s" on base Nil)", name), p_identifier);
					}
					return;
				}
				case Variant::DICTIONARY: {
					GDScriptParser::DataType dummy;
					dummy.kind = GDScriptParser::DataType::VARIANT;
					p_identifier->set_datatype(dummy);
					return;
				}
				default: {
					Callable::CallError temp;
					Variant dummy;
					Variant::construct(base.builtin_type, dummy, nullptr, 0, temp);
					List<PropertyInfo> properties;
					dummy.get_property_list(&properties);
					for (const PropertyInfo &prop : properties) {
						if (prop.name == name) {
							p_identifier->set_datatype(type_from_property(prop));
							return;
						}
					}