This will allow us to fix the validation error related to
VK_KHR_portability_enumeration.
Also, macOS comes with Python 3 nowadays so we're upgrading the script
from Python 2.
This moves all Vulkan entry points into the bluevk namespace
to avoid conflicts with other Vulkan loaders.
This also updates the header files and loader code to version 1.2.159 of
the Vulkan spec, which is currently available at the following links.
https://khronos.org/registry/vulkan/specs/1.2/html/vkspec.html87451c55aa
