### 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_construct);
	REGISTER_INTERFACE_FUNC(variant_get_ptr_setter);
	REGISTER_INTERFACE_FUNC(variant_get_ptr_getter);
	REGISTER_INTERFACE_FUNC(variant_get_ptr_indexed_setter);
	REGISTER_INTERFACE_FUNC(variant_get_ptr_indexed_getter);
	REGISTER_INTERFACE_FUNC(variant_get_ptr_keyed_setter);
	REGISTER_INTERFACE_FUNC(variant_get_ptr_keyed_getter);
	REGISTER_INTERFACE_FUNC(variant_get_ptr_keyed_checker);
	REGISTER_INTERFACE_FUNC(variant_get_constant_value);
	REGISTER_INTERFACE_FUNC(variant_get_ptr_utility_function);
	REGISTER_INTERFACE_FUNC(string_new_with_latin1_chars);
	REGISTER_INTERFACE_FUNC(string_new_with_utf8_chars);
	REGISTER_INTERFACE_FUNC(string_new_with_utf16_chars);
	REGISTER_INTERFACE_FUNC(string_new_with_utf32_chars);
	REGISTER_INTERFACE_FUNC(string_new_with_wide_chars);
	REGISTER_INTERFACE_FUNC(string_new_with_latin1_chars_and_len);
	REGISTER_INTERFACE_FUNC(string_new_with_utf8_chars_and_len);
	REGISTER_INTERFACE_FUNC(string_new_with_utf16_chars_and_len);
	REGISTER_INTERFACE_FUNC(string_new_with_utf32_chars_and_len);
	REGISTER_INTERFACE_FUNC(string_new_with_wide_chars_and_len);
	REGISTER_INTERFACE_FUNC(string_to_latin1_chars);
	REGISTER_INTERFACE_FUNC(string_to_utf8_chars);
	REGISTER_INTERFACE_FUNC(string_to_utf16_chars);
	REGISTER_INTERFACE_FUNC(string_to_utf32_chars);
	REGISTER_INTERFACE_FUNC(string_to_wide_chars);
	REGISTER_INTERFACE_FUNC(string_operator_index);
	REGISTER_INTERFACE_FUNC(string_operator_index_const);
	REGISTER_INTERFACE_FUNC(string_operator_plus_eq_string);
	REGISTER_INTERFACE_FUNC(string_operator_plus_eq_char);
	REGISTER_INTERFACE_FUNC(string_operator_plus_eq_cstr);