### 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
const PackedVector2Array *self = (const PackedVector2Array *)p_self;
	if (unlikely(p_index < 0 || p_index >= self->size())) {
		return nullptr;
	}
	return (GDExtensionTypePtr)&self->ptr()[p_index];
}
static GDExtensionTypePtr gdextension_packed_vector3_array_operator_index(GDExtensionTypePtr p_self, GDExtensionInt p_index) {
	PackedVector3Array *self = (PackedVector3Array *)p_self;
	if (unlikely(p_index < 0 || p_index >= self->size())) {
		return nullptr;
	}
	return (GDExtensionTypePtr)&self->ptrw()[p_index];
}
static GDExtensionTypePtr gdextension_packed_vector3_array_operator_index_const(GDExtensionConstTypePtr p_self, GDExtensionInt p_index) {
	const PackedVector3Array *self = (const PackedVector3Array *)p_self;
	if (unlikely(p_index < 0 || p_index >= self->size())) {
		return nullptr;
	}
	return (GDExtensionTypePtr)&self->ptr()[p_index];
}
static GDExtensionVariantPtr gdextension_array_operator_index(GDExtensionTypePtr p_self, GDExtensionInt p_index) {
	Array *self = (Array *)p_self;
	if (unlikely(p_index < 0 || p_index >= self->size())) {
		return nullptr;
	}
	return (GDExtensionVariantPtr)&self->operator[](p_index);
}
static GDExtensionVariantPtr gdextension_array_operator_index_const(GDExtensionConstTypePtr p_self, GDExtensionInt p_index) {