[NVPTX] Add ELF flags for Nvidia cubin files (#75624)

Summary:
Nvidia uses ELF as its file format for cubin files. This patch adds
support to allow detecting the architecture using the ELF flags only.
This will be used in the offloading runtime in the future.

These values are completely undocumented. They were determined by
manually modifying the ELF header of the cubin and checking the output
of the `nvisasm` tool.