[mlir][sparse] finalize sparse output in the presence of reductions

This revision implements sparse outputs (from scratch) in all cases where
the loops can be reordered with all but one parallel loops outer. If the
inner parallel loop appears inside one or more reductions loops, then an
access pattern expansion is required (aka. workspaces in TACO speak).

Reviewed By: bixia

Differential Revision: https://reviews.llvm.org/D115091