cube: GH1609: Use VK_GOOGLE_display_timing extension

Show how to use the VK_GOOGLE_display_timing extension (currently, only
available on the Android O release).  Other notes:

- There are many diagnostic DbgMsg()'s, which can help show the usage.
- This includes a port of the Vulkan CTS (dEQP) time code for use in
  cube.
- Added a "--display_timing" command-line option to turn on use of
  VK_GOOGLE_display_timing
- Compiles and runs on Windows, Linux, and Android, but the feature will
  only really be used on systems that support the extension.