### 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)


}
						base = look_class->get_datatype();
						found = true;
						break;
					}
					if (look_class->has_member(name)) {
						resolve_class_member(look_class, name, id);
						GDScriptParser::ClassNode::Member member = look_class->get_member(name);
						GDScriptParser::DataType member_datatype = member.get_datatype();
						switch (member.type) {
							case GDScriptParser::ClassNode::Member::CLASS:
								break; 
							case GDScriptParser::ClassNode::Member::CONSTANT:
								if (member_datatype.kind != GDScriptParser::DataType::SCRIPT && member_datatype.kind != GDScriptParser::DataType::CLASS) {
									push_error(vformat(R"(Constant "%s" is not a preloaded script or class.)", name), id);
									return ERR_PARSE_ERROR;
								}
								break;
							default:
								push_error(vformat(R"(Cannot use %s "%s" in extends chain.)", member.get_type_name(), name), id);
								return ERR_PARSE_ERROR;
						}
						base = member_datatype;
						found = true;
						break;
					}
				}
				if (!found) {
					push_error(vformat(R"(Could not find base class "%s".)", name), id);
					return ERR_PARSE_ERROR;