[llvm] [openmp] [clang] [OpenMP] Introduce the KernelLaunchEnvironment as implicit argument (PR #70401)

[Joseph Huber via cfe-commits]

jhuber6 wrote:

Small change that affects a lot of tests. LG once these are fixed:
```
MLIR :: Target/LLVMIR/omptarget-region-device-llvm.mlir
MLIR :: Target/LLVMIR/omptarget-byref-bycopy-generation-device.mlir
MLIR :: Target/LLVMIR/omptarget-declare-target-llvm-device.mlir
```

https://github.com/llvm/llvm-project/pull/70401