### 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 (info.path.get_extension().to_lower() != GDScriptLanguage::get_singleton()->get_extension()) {
					push_error(vformat(R"(Singleton %s is not a GDScript.)", info.name), id);
					return ERR_PARSE_ERROR;
				}
				Ref<GDScriptParserRef> info_parser = get_parser_for(info.path);
				if (info_parser.is_null()) {
					push_error(vformat(R"(Could not parse singleton from "%s".)", info.path), id);
					return ERR_PARSE_ERROR;
				}
				Error err = info_parser->raise_status(GDScriptParserRef::INHERITANCE_SOLVED);
				if (err != OK) {
					push_error(vformat(R"(Could not resolve super class inheritance from "%s".)", name), id);
					return err;
				}
				base = info_parser->get_parser()->head->get_datatype();
			} else if (class_exists(name)) {
				base.kind = GDScriptParser::DataType::NATIVE;
				base.native_type = name;
			} else {
				
				bool found = false;
				List<GDScriptParser::ClassNode *> script_classes;
				get_class_node_current_scope_classes(p_class, &script_classes);
				for (GDScriptParser::ClassNode *look_class : script_classes) {
					if (look_class->identifier && look_class->identifier->name == name) {
						if (!look_class->get_datatype().is_set()) {
							Error err = resolve_class_inheritance(look_class, id);
							if (err) {
								return err;
							}