### 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)


return;
	}
	if (GDScriptLanguage::get_singleton()->has_any_global_constant(name)) {
		Variant constant = GDScriptLanguage::get_singleton()->get_any_global_constant(name);
		p_identifier->set_datatype(type_from_variant(constant, p_identifier));
		p_identifier->is_constant = true;
		p_identifier->reduced_value = constant;
		return;
	}
	if (CoreConstants::is_global_enum(name)) {
		p_identifier->set_datatype(make_global_enum_type(name, StringName(), true));
		if (!can_be_builtin) {
			push_error(vformat(R"(Global enum "%s" cannot be used on its own.)", name), p_identifier);
		}
		return;
	}
	
	if (can_be_builtin && name == SNAME("Variant")) {
		GDScriptParser::DataType variant;
		variant.kind = GDScriptParser::DataType::VARIANT;
		variant.type_source = GDScriptParser::DataType::ANNOTATED_EXPLICIT;
		variant.is_meta_type = true;
		variant.is_pseudo_type = true;
		p_identifier->set_datatype(variant);
		return;
	}
	
	
	if (GDScriptUtilityFunctions::function_exists(name)) {
		push_error(vformat(R"(Built-in function "%s" cannot be used as an identifier.)", name), p_identifier);