### 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
*
 * Creates a script instance that contains the given info and instance data.
 *
 * @param p_info A pointer to a GDExtensionScriptInstanceInfo struct.
 * @param p_instance_data A pointer to a data representing the script instance in the GDExtension. This will be passed to all the function pointers on p_info.
 *
 * @return A pointer to a ScriptInstanceExtension object.
 */
typedef GDExtensionScriptInstancePtr (*GDExtensionInterfaceScriptInstanceCreate)(const GDExtensionScriptInstanceInfo *p_info, GDExtensionScriptInstanceDataPtr p_instance_data);
/**
 * @name script_instance_create2
 * @since 4.2
 *
 * Creates a script instance that contains the given info and instance data.
 *
 * @param p_info A pointer to a GDExtensionScriptInstanceInfo2 struct.
 * @param p_instance_data A pointer to a data representing the script instance in the GDExtension. This will be passed to all the function pointers on p_info.
 *
 * @return A pointer to a ScriptInstanceExtension object.
 */
typedef GDExtensionScriptInstancePtr (*GDExtensionInterfaceScriptInstanceCreate2)(const GDExtensionScriptInstanceInfo2 *p_info, GDExtensionScriptInstanceDataPtr p_instance_data);
/**
 * @name placeholder_script_instance_create
 * @since 4.2
 *
 * Creates a placeholder script instance for a given script and instance.
 *
 * This interface is optional as a custom placeholder could also be created with script_instance_create().
 *
 * @param p_language A pointer to a ScriptLanguage.