[clang] [CIR][OpenMP] Initial implementation of target region support (PR #195452)

[Erich Keane via cfe-commits]

https://github.com/erichkeane commented:

I have a few comments, else I think this looks fine.  I was hoping someone with more OMP & MLIR  knowledge would help (though I see @agozillon at least got most of that), so I don't mind finishing the review.

https://github.com/llvm/llvm-project/pull/195452