### 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)


const StringName &name = p_local->name;
	GDScriptParser::DataType base = parser->current_class->get_datatype();
	GDScriptParser::ClassNode *base_class = base.class_type;
	{
		List<MethodInfo> gdscript_funcs;
		GDScriptLanguage::get_singleton()->get_public_functions(&gdscript_funcs);
		for (MethodInfo &info : gdscript_funcs) {
			if (info.name == name) {
				parser->push_warning(p_local, GDScriptWarning::SHADOWED_GLOBAL_IDENTIFIER, p_context, name, "built-in function");
				return;
			}
		}
		if (Variant::has_utility_function(name)) {
			parser->push_warning(p_local, GDScriptWarning::SHADOWED_GLOBAL_IDENTIFIER, p_context, name, "built-in function");
			return;
		} else if (ClassDB::class_exists(name)) {
			parser->push_warning(p_local, GDScriptWarning::SHADOWED_GLOBAL_IDENTIFIER, p_context, name, "global class");
			return;
		} else if (GDScriptParser::get_builtin_type(name) != Variant::VARIANT_MAX) {
			parser->push_warning(p_local, GDScriptWarning::SHADOWED_GLOBAL_IDENTIFIER, p_context, name, "built-in type");
			return;
		}
	}
	while (base_class != nullptr) {