[llvm] [Delinearization] Add function for fixed size array without relying on GEP (PR #145050)

[Ryotaro Kasuga via llvm-commits]

kasuga-fj wrote:

I looked into the details of changes in the results when replacing the current `tryDelinearizeFixedSizeImpl` in DA with the new function `delinearizeFixedSizeArray`, and found the two issues (#148241 and #148813) on the DA side. However, the new function seems to behave correctly. So I believe this PR is ready to merge.

https://github.com/llvm/llvm-project/pull/145050