[mlir][sparse] add a sparse quantized_matmul example to integration test

Note that this revision adds a very tiny bit of constant folding in the
sparse compiler lattice construction. Although I am generally trying to
avoid such canonicalizations (and rely on other passes to fix this instead),
the benefits of avoiding a very expensive disjunction lattice construction
justify having this special code (at least for now).

Reviewed By: bixia

Differential Revision: https://reviews.llvm.org/D109939