[mlir][vector] Add apply_patterns.vector.multi_reduction_unrolling. (#182113)
* Adds vector transform op
`apply_patterns.vector.multi_reduction_unrolling`
* Adds test for `populateVectorMultiReductionUnrollingPatterns`
* Deletes old test files `vector-multi-reduction-lowering.mlir` and
`vector-multi-reduction-lowering-outer.mlir`. Tests that exercise these
patterns exist in `vector-multi-reduction-flattening.mlir`,
`vector-multi-reduction-reorder-and-expand.mlir` and
`vector-multi-reduction-unrolling.mlir`
Assisted-by: claude