[llvm] [offload][SYCL] Add SYCL Module splitting (PR #119713)

[Maksim Sabianin via llvm-commits]

================

----------------
maksimsab wrote:

The splitting algorithm in this PR was simplified for initial PR. Other parts are going to be added on top of the initial PR. There are upcoming `auto-module-split-{2,3}.ll` tests that correspond to missed functionality.
They can be observer here: https://github.com/intel/llvm/tree/sycl-web/status/llvm/test/tools/sycl-post-link/device-code-split

https://github.com/llvm/llvm-project/pull/119713