benchmarks/vkpeak: add new port

vkpeak is a synthetic benchmarking tool to measure peak capabilities
of Vulkan devices. It only measures the peak metrics that can be
achieved using vector operations and does not represent a real-world
use case.

https://github.com/nihui/vkpeak
(cherry picked from commit 9e9d84f60dbe5c74c3ea03dff185ce22eba69a96)