[clang] [mlir] [OpenACC][CIR] Implement 'exit data' construct + clauses (PR #146167)

[Erich Keane via cfe-commits]

erichkeane wrote:

Sorry for the force-push, screwed up the clang-format commit and rather than spending time backing it out, i hoped no one would be affected.

https://github.com/llvm/llvm-project/pull/146167