[clang] [clang] Introduce `SemaCoroutine` (PR #92645)

[Erich Keane via cfe-commits]

erichkeane wrote:

FWIW, I've been working actively on Open ACC Sema, and I found that the split so far has made development much more organized/easier, and makes naming of things a lot less awkward.  I realize splitting out actual language features is concerning to some, but I'm cautiously optimistic with how successful I think the split of some of the dialects have been.



https://github.com/llvm/llvm-project/pull/92645