### 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)


callee_id = static_cast<GDScriptParser::IdentifierNode *>(p_call->callee);
			} else {
				
				callee_id = static_cast<GDScriptParser::SubscriptNode *>(p_call->callee)->attribute;
			}
			if (callee_id) {
				reduce_identifier_from_base(callee_id, &base_type);
				GDScriptParser::DataType callee_datatype = callee_id->get_datatype();
				if (callee_datatype.is_set() && !callee_datatype.is_variant()) {
					found = true;
					if (callee_datatype.builtin_type == Variant::CALLABLE) {
						push_error(vformat(R"*(Name "%s" is a Callable. You can call it with "%s.call()" instead.)*", p_call->function_name, p_call->function_name), p_call->callee);
					} else {
						push_error(vformat(R"*(Name "%s" called as a function but is a "%s".)*", p_call->function_name, callee_datatype.to_string()), p_call->callee);
					}
#ifdef DEBUG_ENABLED
				} else if (!is_self && !(base_type.is_hard_type() && base_type.kind == GDScriptParser::DataType::BUILTIN)) {
					parser->push_warning(p_call, GDScriptWarning::UNSAFE_METHOD_ACCESS, p_call->function_name, base_type.to_string());
					mark_node_unsafe(p_call);
#endif
				}
			}
		}
		if (!found && (is_self || (base_type.is_hard_type() && base_type.kind == GDScriptParser::DataType::BUILTIN))) {
			String base_name = is_self && !p_call->is_super ? "self" : base_type.to_string();
#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_function_name = check_for_renamed_identifier(p_call->function_name, p_call->type);
				if (renamed_function_name) {