layers: Write helpers for UO Unwrap+WrapNew operations
layers: Write helpers for UO Unwrap+WrapNew operations

Allows us to concentrate all the ID generation and cast insanity in one
place.

KhronosGroup/Vulkan-LoaderAndValidationLayers,KhronosGroup/Vulkan-LoaderAndValidationLayers,KhronosGroup/Vulkan-LoaderAndValidationLayers,KhronosGroup/Vulkan-LoaderAndValidationLayers