### 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_property.usage & PROPERTY_USAGE_CLASS_IS_ENUM) && p_property.class_name != StringName()) {
				if (CoreConstants::is_global_enum(p_property.class_name)) {
					result = make_global_enum_type(p_property.class_name, StringName(), false);
					result.is_constant = false;
				} else {
					Vector<String> names = String(p_property.class_name).split(ENUM_SEPARATOR);
					if (names.size() == 2) {
						result = make_native_enum_type(names[1], names[0], false);
						result.is_constant = false;
					}
				}
			}
			
		}
	}
	return result;
}
bool GDScriptAnalyzer::get_function_signature(GDScriptParser::Node *p_source, bool p_is_constructor, GDScriptParser::DataType p_base_type, const StringName &p_function, GDScriptParser::DataType &r_return_type, List<GDScriptParser::DataType> &r_par_types, int &r_default_arg_count, BitField<MethodFlags> &r_method_flags, StringName *r_native_class) {
	r_method_flags = METHOD_FLAGS_DEFAULT;
	r_default_arg_count = 0;
	if (r_native_class) {
		*r_native_class = StringName();
	}
	StringName function_name = p_function;
	bool was_enum = false;
	if (p_base_type.kind == GDScriptParser::DataType::ENUM) {
		was_enum = true;
		if (p_base_type.is_meta_type) {
			
			p_base_type.kind = GDScriptParser::DataType::BUILTIN;