Re-add previously reverted behavior that allows layers to setup dispatch chains for unknown physical
device and device functions during vkCreateInstance. Previously, functions not known to the loader could not
be queried by a layer during vkCreateInstance (when dispatch tables should be setup). The change adds support
for unknown functions in the trampolines of vkGetInstanceProcAddr and vkGetPhysicalDeviceProcAddr.
Unknown Device functions not listed in a layers manifest will now be found through vkGetInstanceProcAddr,
which was previously not used.
When checking for unknown physical device functions, check the first layer that supports
vk_layerGetPhysicalDeviceProcAddr in the chain starting with the layer closest to the
application. This prevents unecessary work being done, and if any layer wraps VkInstance
will properly call through the wrapping layer first without calling into any other layer.
andrew0229