[mlir][Linalg] SplitReduction implementation without tensor::ExpandShapeOp

This revision proposes a different implementation of the SplitReductoin transformation that does
not rely on tensor::ExpandShapeOp.

Previously, a dimension `[k]` would be split into `[k][kk]` via an ExpandShapeOp.
Instead, this revision proposes to rewrite `[k]` into `[factor * k + kk]`.

There are different tradeoffs involved  but the proposed implementation is more general because
the affine rewrite is well-defined. In particular, it works naturally with `?` parallel dimensions and
non-trivial indexing maps.

A further rewrite of `[factor * k + kk]` + ExpandShapeOp is possible as a followup.

Differential Revision: https://reviews.llvm.org/D128266