Refactor CDI pkg out of toolkit repo

[myeolenv]

[karthikvetrivel]

Some more context on this issue:

The idea is to extract https://github.com/NVIDIA/nvidia-container-toolkit/tree/main/pkg/nvcdi into go-nvlib so that other repos, like k8s-device-plugin / dra-driver, which import this go package do not need to depend on the NVIDIA Container Toolkit repository.

The nvcdi package is the NVIDIA code that generates CDI specs.