[clang] [CIR] Upstream initial support for unary op (PR #131369)

[Erich Keane via cfe-commits]

https://github.com/erichkeane commented:

I still have the open question on that comment I'd like an answer to, but 1 suggestion here.  Else this LGTM.

https://github.com/llvm/llvm-project/pull/131369