[mlir] Add support for static unpack op vectorization without providing inpu… (PR #89067)

[Andrzej Warzyński]

banach-space wrote:

[nit] Could you trim the commit subject? It's much easier to read if it fits in one line. Also:
* https://mlir.llvm.org/getting_started/Contributing/#commit-messages --> https://cbea.ms/git-commit/#limit-50

Thanks :)

https://github.com/llvm/llvm-project/pull/89067