### 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
typedef void (*GDExtensionScriptInstanceToString)(GDExtensionScriptInstanceDataPtr p_instance, GDExtensionBool *r_is_valid, GDExtensionStringPtr r_out);
typedef void (*GDExtensionScriptInstanceRefCountIncremented)(GDExtensionScriptInstanceDataPtr p_instance);
typedef GDExtensionBool (*GDExtensionScriptInstanceRefCountDecremented)(GDExtensionScriptInstanceDataPtr p_instance);
typedef GDExtensionObjectPtr (*GDExtensionScriptInstanceGetScript)(GDExtensionScriptInstanceDataPtr p_instance);
typedef GDExtensionBool (*GDExtensionScriptInstanceIsPlaceholder)(GDExtensionScriptInstanceDataPtr p_instance);
typedef void *GDExtensionScriptLanguagePtr;
typedef GDExtensionScriptLanguagePtr (*GDExtensionScriptInstanceGetLanguage)(GDExtensionScriptInstanceDataPtr p_instance);
typedef void (*GDExtensionScriptInstanceFree)(GDExtensionScriptInstanceDataPtr p_instance);
typedef void *GDExtensionScriptInstancePtr; 
typedef struct {
	GDExtensionScriptInstanceSet set_func;
	GDExtensionScriptInstanceGet get_func;
	GDExtensionScriptInstanceGetPropertyList get_property_list_func;
	GDExtensionScriptInstanceFreePropertyList free_property_list_func;
	GDExtensionScriptInstancePropertyCanRevert property_can_revert_func;
	GDExtensionScriptInstancePropertyGetRevert property_get_revert_func;
	GDExtensionScriptInstanceGetOwner get_owner_func;
	GDExtensionScriptInstanceGetPropertyState get_property_state_func;
	GDExtensionScriptInstanceGetMethodList get_method_list_func;
	GDExtensionScriptInstanceFreeMethodList free_method_list_func;
	GDExtensionScriptInstanceGetPropertyType get_property_type_func;
	GDExtensionScriptInstanceHasMethod has_method_func;
	GDExtensionScriptInstanceCall call_func;
	GDExtensionScriptInstanceNotification notification_func;
	GDExtensionScriptInstanceToString to_string_func;
	GDExtensionScriptInstanceRefCountIncremented refcount_incremented_func;
	GDExtensionScriptInstanceRefCountDecremented refcount_decremented_func;
	GDExtensionScriptInstanceGetScript get_script_func;
	GDExtensionScriptInstanceIsPlaceholder is_placeholder_func;
	GDExtensionScriptInstanceSet set_fallback_func;