layers:Moving to GPDF2
layers:Moving to GPDF2

Update layer_data struct to track safe_VkPhysicalDeviceFeatures2 struct
instead of VkPhysicalDeviceFeatures. Currently just doing previous
checks using the VkPhysicalDeviceFeatures member of GPDF2 struct. Will
follow-on with checking against extension structs.

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