graphics/py-vulkan: Python binding for Vulkan API

vulkan is a Python extension which supports the Vulkan API. It
leverages power of Vulkan with simplicity of Python. It's a complete
Vulkan wrapper, it keeps the original Vulkan API and try to limit
differences induced by Python.

devel/py-cffi is also needed as a BUILD_DEPENDS (truckman)

PR: 289669