[mlir][linalg][transform] Rename {masked_vectorize => vectorize =>...

[mlir][linalg][transform] Rename {masked_vectorize => vectorize => vectorize_children_and...}. (#66575)

This PR renames the vectorization transform ops as follows:

* `structured.masked_vectorize` => `structured.vectorize`. This reflects
the fact that since [recently](https://reviews.llvm.org/D157774) the op
can also handle the unmasked case.
* `structured.vectorize` =>
`structured.vectorize_children_and_applies_patterns`. This reflects the
fact that the op does not just vectorize the given payload op but all
vectorizable children contained in it, and applies patterns before and
after for preparation and clean-up.

This rename was discussed first
[here](https://reviews.llvm.org/D157774).

The PR also adapts and cleans ups the tablegen description of the
`VectorizeChildrenAndApplyPatternsOp` (formerly `VectorizeOp`).