### 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) {
							if (argument->reduced_value.get_type() != Variant::INT && argument->reduced_value.get_type() != Variant::FLOAT) {
								can_reduce = false;
								push_error(vformat(R"*(Invalid argument for "range()" call. Argument %d should be int or float but "%s" was given.)*", i + 1, Variant::get_type_name(argument->reduced_value.get_type())), argument);
							}
							if (can_reduce) {
								args.write[i] = argument->reduced_value;
							}
						} else {
							can_reduce = false;
							GDScriptParser::DataType argument_type = argument->get_datatype();
							if (argument_type.is_variant() || !argument_type.is_hard_type()) {
								mark_node_unsafe(argument);
							}
							if (!argument_type.is_variant() && (argument_type.builtin_type != Variant::INT && argument_type.builtin_type != Variant::FLOAT)) {
								if (!argument_type.is_hard_type()) {
									downgrade_node_type_source(argument);
								} else {
									push_error(vformat(R"*(Invalid argument for "range()" call. Argument %d should be int or float but "%s" was given.)*", i + 1, argument_type.to_string()), argument);
								}
							}
						}
					}
					Variant reduced;
					if (can_reduce) {
						switch (args.size()) {
							case 1:
								reduced = (int32_t)args[0];
								break;
							case 2: