[NVPTX] Add builtin support for 'nanosleep' PTX instrunction (#79888)

Summary:
This patch adds a builtin for the `nanosleep` PTX function. It takes
either an immediate or a register and sleeps for [0, 2t] nanoseconds
given t. More information at the documentation:

https://docs.nvidia.com/cuda/parallel-thread-execution/index.html#miscellaneous-instructions-nanosleep