[mlir][linalg][transform][python] Extend mix-in for Vectorize

Extends the existing mix-in for VectorizeOp with support for the missing unit attributes.

Also fixes the unintuitive implementation where
`structured.VectorizeOp(target=target, vectorize_padding=False)` still resulted in the creation of the UnitAttr `vectorize_padding`.

Reviewed By: ingomueller-net

Differential Revision: https://reviews.llvm.org/D158726