layers: Create instance & device extension lists
layers: Create instance & device extension lists

Added constant lists of device and instance extension names to
vk_extension_helper.h.

Change-Id: I4273aea866cbfea176a2631e04223ce92443caf0

KhronosGroup/Vulkan-Tools,KhronosGroup/Vulkan-Tools,KhronosGroup/Vulkan-Tools,KhronosGroup/Vulkan-Tools