[clang] [CIR] Implement initial flattening of cleanup scope ops (PR #180063)

[Bruno Cardoso Lopes via cfe-commits]

https://github.com/bcardosolopes approved this pull request.

LGTM! I think it would be a nice addition to have the passing c++ tests that lead to these CIR entries covered as well (instead of just cir to cir).

https://github.com/llvm/llvm-project/pull/180063