### 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)


Variant result = Variant();
	if (p_variable->initializer) {
		bool is_initializer_value_reduced = false;
		Variant initializer_value = make_expression_reduced_value(p_variable->initializer, is_initializer_value_reduced);
		if (is_initializer_value_reduced) {
			result = initializer_value;
		}
	} else {
		GDScriptParser::DataType datatype = p_variable->get_datatype();
		if (datatype.is_hard_type()) {
			if (datatype.kind == GDScriptParser::DataType::BUILTIN && datatype.builtin_type != Variant::OBJECT) {
				if (datatype.builtin_type == Variant::ARRAY && datatype.has_container_element_type()) {
					result = make_array_from_element_datatype(datatype.get_container_element_type());
				} else {
					VariantInternal::initialize(&result, datatype.builtin_type);
				}
			} else if (datatype.kind == GDScriptParser::DataType::ENUM) {
				result = 0;
			}
		}
	}
	return result;
}
GDScriptParser::DataType GDScriptAnalyzer::type_from_variant(const Variant &p_value, const GDScriptParser::Node *p_source) {