[clang] [CIR] Implement PromotableRegionOpInterface for `cir.if`,`cir.scope` and `cir.ternary` (PR #215780)

[Henrich Lauko via cfe-commits]

https://github.com/xlauko commented:

Can we make this complete for all other ops:
- cir.for, cir.while, cir.do
- cir.switch and cir.case
- cir.cleanup.scope and cir.try



https://github.com/llvm/llvm-project/pull/215780