Implement objects associated with VkSurface

Implement objects associated with VkSurface

Defines an abstract wsi::surface object to be implemented by each WSI
backend. This object is then associated with the corresponding VkSurface
object in the instance specific data.

To keep track of these objects the layer now intercepts
vkDestroySurfaceKHR, while specific surface creation entrypoints are
intercepted by individual WSI backends.

In addition this change should allow for fixing incompatibility issues
with layers that wrap VkSurface which breaks casting to the Loader's ICD
VkSurface type.

Make greater use of util::unique_ptr and allow for such pointers to be
constructable when casting derived types.

Change-Id: I163e9c47088ad9989583ebce1319b1fc05559d73
Signed-off-by: Rosen Zhelev <rosen.zhelev@arm.com>