### 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
}
		return Ref<Script>();
	}
	virtual bool is_placeholder() const override {
		if (native_info->is_placeholder_func) {
			return native_info->is_placeholder_func(instance);
		}
		return false;
	}
	virtual void property_set_fallback(const StringName &p_name, const Variant &p_value, bool *r_valid) override {
		if (native_info->set_fallback_func) {
			bool ret = native_info->set_fallback_func(instance, (GDExtensionConstStringNamePtr)&p_name, (GDExtensionConstVariantPtr)&p_value);
			if (r_valid) {
				*r_valid = ret;
			}
		}
	}
	virtual Variant property_get_fallback(const StringName &p_name, bool *r_valid) override {
		Variant ret;
		if (native_info->get_fallback_func) {
			bool valid = native_info->get_fallback_func(instance, (GDExtensionConstStringNamePtr)&p_name, (GDExtensionVariantPtr)&ret);
			if (r_valid) {
				*r_valid = valid;
			}
		}
		return ret;
	}
	virtual ScriptLanguage *get_language() override {
		if (native_info->get_language_func) {
			GDExtensionScriptLanguagePtr lang = native_info->get_language_func(instance);
			return reinterpret_cast<ScriptLanguage *>(lang);
		}
		return nullptr;
		;
	}
	virtual ~ScriptInstanceExtension() {
		if (native_info->free_func) {
			native_info->free_func(instance);
		}
		if (free_native_info) {
			memfree(const_cast<GDExtensionScriptInstanceInfo2 *>(native_info));
		}
	}
#if defined(__GNUC__) && !defined(__clang__)
#pragma GCC diagnostic pop
#endif
};
#endif 
