[vulkan] Better error message when failing to make vulkan device. (#372)
[vulkan] Better error message when failing to make vulkan device. (#372)

This CL updates the sample app to list the requested extensions and
features when we fail to create a Vulkan device. This makes it a bit
clearer as to why the device creation failed.

Issue #336
google/amber,google/amber,google/amber,google/amber,google/amber