[Clang] Initial support for linking offloading code in tool

This patch adds the initial support for linking NVPTX offloading code
using the clang-linker-wrapper tool. This uses the extracted device
files and runs `nvlink` on them. Currently this is then passed to the
existing toolchain for creating linkable OpenMP offloading programs
using `clang-offload-wrapper` and compiling it manually using `llc`.
More work is required to support LTO, Bitcode linking, AMDGPU, and x86
offloading.

Depends on D116545

Differential Revision: https://reviews.llvm.org/D116627