### 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)


rename_hint = " " + vformat(R"(Did you mean to use "%s"?)", String(renamed_function_name) + "()");
				}
			}
			push_error(vformat(R"*(Function "%s()" not found in base %s.%s)*", p_call->function_name, base_name, rename_hint), p_call->is_super ? p_call : p_call->callee);
#else
			push_error(vformat(R"*(Function "%s()" not found in base %s.)*", p_call->function_name, base_name), p_call->is_super ? p_call : p_call->callee);
#endif 
		} else if (!found && (!p_call->is_super && base_type.is_hard_type() && base_type.kind == GDScriptParser::DataType::NATIVE && base_type.is_meta_type)) {
			push_error(vformat(R"*(Static function "%s()" not found in base "%s".)*", p_call->function_name, base_type.native_type), p_call);
		}
	}
	if (call_type.is_coroutine && !p_is_await && !p_is_root) {
		push_error(vformat(R"*(Function "%s()" is a coroutine, so it must be called with "await".)*", p_call->function_name), p_call);
	}
	p_call->set_datatype(call_type);
}
void GDScriptAnalyzer::reduce_cast(GDScriptParser::CastNode *p_cast) {
	reduce_expression(p_cast->operand);
	GDScriptParser::DataType cast_type = type_from_metatype(resolve_datatype(p_cast->cast_type));
	if (!cast_type.is_set()) {
		mark_node_unsafe(p_cast);
		return;
	}
	p_cast->set_datatype(cast_type);
	if (p_cast->operand->is_constant) {
		update_const_expression_builtin_type(p_cast->operand, cast_type, "cast", true);
		if (cast_type.is_variant() || p_cast->operand->get_datatype() == cast_type) {
			p_cast->is_constant = true;
			p_cast->reduced_value = p_cast->operand->reduced_value;
		}