### Godot version

4.2 247c354

### System information

Windows 10.0.19045 - Vulkan (Forward+) - dedicated NVIDIA GeForce GTX 1060 (NVIDIA; 30.0.15.1403) - Intel(R) Core(TM) i7-7700HQ CPU @ 2.80GHz (8 Threads)

### Issue description

#75778 exposed `_validate_property()` to scripting. It's implemented in GDScript and C#, but not GDExtension (depends on #78634).
https://github.com/godotengine/godot/blob/247c3548d810136ffe9c1694cd76db3236efaa90/core/object/script_language_extension.h#L685-L687

Relevant discussion: https://github.com/godotengine/godot/pull/75778#discussion_r1307294940

### Steps to reproduce

1. Add GDExtension script
2. Use `_validate_property()`

### Minimal reproduction project

N/A
REGISTER_INTERFACE_FUNC(variant_set);
	REGISTER_INTERFACE_FUNC(variant_set_named);
	REGISTER_INTERFACE_FUNC(variant_set_keyed);
	REGISTER_INTERFACE_FUNC(variant_set_indexed);
	REGISTER_INTERFACE_FUNC(variant_get);
	REGISTER_INTERFACE_FUNC(variant_get_named);
	REGISTER_INTERFACE_FUNC(variant_get_keyed);
	REGISTER_INTERFACE_FUNC(variant_get_indexed);
	REGISTER_INTERFACE_FUNC(variant_iter_init);
	REGISTER_INTERFACE_FUNC(variant_iter_next);
	REGISTER_INTERFACE_FUNC(variant_iter_get);
	REGISTER_INTERFACE_FUNC(variant_hash);
	REGISTER_INTERFACE_FUNC(variant_recursive_hash);
	REGISTER_INTERFACE_FUNC(variant_hash_compare);
	REGISTER_INTERFACE_FUNC(variant_booleanize);
	REGISTER_INTERFACE_FUNC(variant_duplicate);
	REGISTER_INTERFACE_FUNC(variant_stringify);
	REGISTER_INTERFACE_FUNC(variant_get_type);
	REGISTER_INTERFACE_FUNC(variant_has_method);
	REGISTER_INTERFACE_FUNC(variant_has_member);
	REGISTER_INTERFACE_FUNC(variant_has_key);
	REGISTER_INTERFACE_FUNC(variant_get_type_name);
	REGISTER_INTERFACE_FUNC(variant_can_convert);
	REGISTER_INTERFACE_FUNC(variant_can_convert_strict);
	REGISTER_INTERFACE_FUNC(get_variant_from_type_constructor);
	REGISTER_INTERFACE_FUNC(get_variant_to_type_constructor);
	REGISTER_INTERFACE_FUNC(variant_get_ptr_operator_evaluator);
	REGISTER_INTERFACE_FUNC(variant_get_ptr_builtin_method);
	REGISTER_INTERFACE_FUNC(variant_get_ptr_constructor);
	REGISTER_INTERFACE_FUNC(variant_get_ptr_destructor);