### 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)


p_identifier->set_datatype(type_from_metatype(base));
				p_identifier->is_constant = true;
				p_identifier->reduced_value = base.enum_values[name];
				return;
			}
			
			return;
		} else {
			push_error(R"(Cannot get property from enum value.)", p_identifier);
			return;
		}
	}
	if (base.kind == GDScriptParser::DataType::BUILTIN) {
		if (base.is_meta_type) {
			bool valid = true;
			Variant result = Variant::get_constant_value(base.builtin_type, name, &valid);
			if (valid) {
				p_identifier->is_constant = true;
				p_identifier->reduced_value = result;
				p_identifier->set_datatype(type_from_variant(result, p_identifier));
			} else if (base.is_hard_type()) {
#ifdef SUGGEST_GODOT4_RENAMES
				String rename_hint = String();
				if (GLOBAL_GET(GDScriptWarning::get_settings_path_from_code(GDScriptWarning::Code::RENAMED_IN_GODOT_4_HINT)).booleanize()) {
					const char *renamed_identifier_name = check_for_renamed_identifier(name, p_identifier->type);
					if (renamed_identifier_name) {
						rename_hint = " " + vformat(R"(Did you mean to use "%s"?)", renamed_identifier_name);
					}
				}
				push_error(vformat(R"(Cannot find constant "%s" on base "%s".%s)", name, base.to_string(), rename_hint), p_identifier);