### 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 (ClassDB::has_signal(p_native_type_string, p_member_name)) {
		return true;
	}
	if (ClassDB::has_property(p_native_type_string, p_member_name)) {
		return true;
	}
	if (ClassDB::has_integer_constant(p_native_type_string, p_member_name)) {
		return true;
	}
	if (p_member_name == CoreStringNames::get_singleton()->_script) {
		return true;
	}
	return false;
}
Error GDScriptAnalyzer::check_native_member_name_conflict(const StringName &p_member_name, const GDScriptParser::Node *p_member_node, const StringName &p_native_type_string) {
	if (has_member_name_conflict_in_native_type(p_member_name, p_native_type_string)) {
		push_error(vformat(R"(Member "%s" redefined (original in native class '%s'))", p_member_name, p_native_type_string), p_member_node);
		return ERR_PARSE_ERROR;
	}
	if (class_exists(p_member_name)) {
		push_error(vformat(R"(The member "%s" shadows a native class.)", p_member_name), p_member_node);
		return ERR_PARSE_ERROR;
	}
	if (GDScriptParser::get_builtin_type(p_member_name) != Variant::VARIANT_MAX) {
		push_error(vformat(R"(The member "%s" cannot have the same name as a builtin type.)", p_member_name), p_member_node);
		return ERR_PARSE_ERROR;
	}
	return OK;
}
Error GDScriptAnalyzer::check_class_member_name_conflict(const GDScriptParser::ClassNode *p_class_node, const StringName &p_member_name, const GDScriptParser::Node *p_member_node) {