### 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 (!p_preload->path) {
		return;
	}
	reduce_expression(p_preload->path);
	if (!p_preload->path->is_constant) {
		push_error("Preloaded path must be a constant string.", p_preload->path);
		return;
	}
	if (p_preload->path->reduced_value.get_type() != Variant::STRING) {
		push_error("Preloaded path must be a constant string.", p_preload->path);
	} else {
		p_preload->resolved_path = p_preload->path->reduced_value;
		
		if (p_preload->resolved_path.is_relative_path()) {
			p_preload->resolved_path = parser->script_path.get_base_dir().path_join(p_preload->resolved_path);
		}
		p_preload->resolved_path = p_preload->resolved_path.simplify_path();
		if (!ResourceLoader::exists(p_preload->resolved_path)) {
			Ref<FileAccess> file_check = FileAccess::create(FileAccess::ACCESS_RESOURCES);
			if (file_check->file_exists(p_preload->resolved_path)) {
				push_error(vformat(R"(Preload file "%s" has no resource loaders (unrecognized file extension).)", p_preload->resolved_path), p_preload->path);
			} else {
				push_error(vformat(R"(Preload file "%s" does not exist.)", p_preload->resolved_path), p_preload->path);
			}
		} else {
			
			
			
			if (ResourceLoader::get_resource_type(p_preload->resolved_path) == "GDScript") {
				Error err = OK;