[linalg][fusion] Disallow fusion when it would create an invalid expand_shape

The input type of a linalg.generic can be less dynamic than its output
type. If this is the case moving a reshape across the generic op would
create invalid IR, as expand_shape cannot expand arbitrary dynamic
dimensions.

Check that the reshape is actually valid before creating the
expand_shape. This exposes the existing verification logic in reshape
utils and removes the incomplete custom implementation in fusion.

Differential Revision: https://reviews.llvm.org/D116600