This PR adds the UB to LLVM/SPIR-V conversion pass to some pipelines and
tests. This is in preparation to introducing the generation of
`ub.poison` in Vector dialect transformations (first one in https://github.com/llvm/llvm-project/pull/125613).
It should effectively be NFC at this point.
### Description
This PR builds on #99872. It implements a minimal version of function
body vector unrolling to convert vector types into 1D and with a size
supported by SPIR-V (2, 3 or 4 depending on the original dimension). The
ops that are currently supported include those with elementwise traits
(e.g. `arith.addi`), `vector.reduction` and `vector.transpose`. This PR
also includes new LIT tests that only check for vector unrolling.
### Future Plans
- Support more ops
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Co-authored-by: Jakub Kuderski <kubakuderski@gmail.com>
