[clang] [CIR][OpenMP] Add support for combined target parallel directives (PR #207019)

[Sergio Afonso via cfe-commits]

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

Thanks again Jan, LGTM. Just some nits/questions from me, but nothing blocking from my side.

I don't have much experience with the construct decomposition logic, so it would be best if Krzysztof could take a look at that part before merging.

https://github.com/llvm/llvm-project/pull/207019