Let `memref.expand_shape` implement `ReifyRankedShapedTypeOpInterface` (#90975)

This is a new take on #89111. Now that #90040 is merged, this has become
trivial to implement. The added test shows the kind of benefit that we
get from this: now dim-of-expand-shape naturally folds without us
needing to implement an ad-hoc folding rewrite.