This is a follow-up for #81790. This patch basically extends:
* test/Integration/Dialect/Linalg/CPU/mmt4d.mlir
with pack/unpack ops so that to overall computation is a matrix
multiplication (as opposed to linalg.mmt4d). For comparison (and to make
it easier to verify correctness), linalg.matmul is also included in the
test.
d7753989ea