### 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
* @since 4.1
 *
 * Appends a character to a String.
 *
 * @param p_self A pointer to the String.
 * @param p_b A pointer to the character to append.
 */
typedef void (*GDExtensionInterfaceStringOperatorPlusEqChar)(GDExtensionStringPtr p_self, char32_t p_b);
/**
 * @name string_operator_plus_eq_cstr
 * @since 4.1
 *
 * Appends a Latin-1 encoded C string to a String.
 *
 * @param p_self A pointer to the String.
 * @param p_b A pointer to a Latin-1 encoded C string (null terminated).
 */
typedef void (*GDExtensionInterfaceStringOperatorPlusEqCstr)(GDExtensionStringPtr p_self, const char *p_b);
/**
 * @name string_operator_plus_eq_wcstr
 * @since 4.1
 *
 * Appends a wide C string to a String.
 *
 * @param p_self A pointer to the String.
 * @param p_b A pointer to a wide C string (null terminated).
 */
typedef void (*GDExtensionInterfaceStringOperatorPlusEqWcstr)(GDExtensionStringPtr p_self, const wchar_t *p_b);
/**
 * @name string_operator_plus_eq_c32str