[Clang] Add __scoped_atomic_uinc_wrap and __scoped_atomic_udec_wrap builtins (#168666)
This PR extends __scoped_atomic builtins with inc and dec functions.
They map to LLVM IR `atomicrmw uinc_wrap` and `atomicrmw udec_wrap`.
These enable implementation of OpenCL-style atomic_inc / atomic_dec with
wrap semantics on targets supporting scoped atomics (e.g. GPUs).
---------
Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>