[clang] [Clang][SYCL] Introduce clang-sycl-link-wrapper to link SYCL offloading device code (Part 1 of many) (PR #112245)

[Joseph Huber via cfe-commits]

jhuber6 wrote:

> Why is this a clang-based tool? Other than using clang/Basic to get the clang version (which could also be retrieved from LLVM), this doesn't seem to have any dependencies on Clang.
> 
> As I'm seeing the SYCL patches coming in I'm getting concerned that the architecture of the SYCL compiler doesn't align with LLVM and Clang's design.

Realistically it doesn't need to be, despite the fact that clang wants to use it. The goal is to just have a tool that clang can use as a normal toolchain linker so we can reuse as much as possible when it comes to creating link jobs. We could stash this in `llvm/` and it wouldn't make much of a difference. Also we can probably just use the LLVM Linker API instead of `llvm-link`. Forgot to mention that as a to-do.

https://github.com/llvm/llvm-project/pull/112245