[mlir][shape] Add `shape.cstr_require %bool`

This op is a catch-all for creating witnesses from various random kinds
of constraints. In particular, I when dealing with extents directly,
which are of `index` type, one can directly use std ops for calculating
the predicates, and then use cstr_require for the final conversion to a
witness.

Differential Revision: https://reviews.llvm.org/D87871