[clang] [CIR] Upstream TernaryOp for VectorType (PR #142393)

[Henrich Lauko via cfe-commits]

xlauko wrote:

> * `IntegerVector:$cond` will replaced by `CIR_VectorOfIntType` after merging [[CIR][NFC] Upstream VectorType support in helper function #142222](https://github.com/llvm/llvm-project/pull/142222)
> * there will be a follow up PR for the folder

To simplify these kind of dependencies in PRs I suggest stacked PRs in the future, it would allow you to use  `CIR_VectorOfIntType` here and mark that this PR needs [[CIR][NFC] Upstream VectorType support in helper function #142222](https://github.com/llvm/llvm-project/pull/142222) 

LLVM docs has some guidance on this: https://llvm.org/docs/GitHub.html#stacked-pull-requests

I am personally using graphite, which has also pretty good interactive demo tutorial.

https://github.com/llvm/llvm-project/pull/142393