[llvm] [Coroutines] Split buildCoroutineFrame into normalization and frame building (PR #108076)

[Tyler Nowicki via llvm-commits]

TylerNowicki wrote:

> Overall I think a neutral/positive change. One thing I am worried was that how we are going to distinguish a "normalized" vs a "unnormalized" coroutine? i.e. How do we find out that we missed a normalization here?

I posted a PR to add a couple of asserts that check for normalization. The PR includes this change (I posted it too quickly), I will rebase after this change merges.

https://github.com/llvm/llvm-project/pull/108096

https://github.com/llvm/llvm-project/pull/108076