[mlir][vector] Add a custom builder for LowerVectorsOp

The `lower_vectors` operation of the transform dialect takes a lot of
arguments to build.
In order to make C++ code easier to work with when using this
instruction, introduce a new structure, named `LowerVectorsOptions`, that
aggregates all the options that are used to build this instruction.

This allows to use patterns like:
```
LowerVectorsOptions opts;
opts.setOptZ(...)
  .setOptY(...)...;
builder.create<LowerVectorsOp>(target, opts);
```

Instead of having to pass all N options directly to the builder and set
them in the right order.

NFC

Differential Revision: https://reviews.llvm.org/D141923