The `ShapeOfOp` folder used to generate invalid IR.
Input:
```
%0 = shape.shape_of %arg1 : tensor<index> -> tensor<?xindex>
```
Output:
```
%0 = "shape.const_shape"() <{shape = dense<> : tensor<0xindex>}> : () -> tensor<?xindex>
error: 'shape.const_shape' op inferred type(s) 'tensor<0xindex>' are incompatible with return type(s) of operation 'tensor<?xindex>'
```
This rewrite cannot be implemented as a folder because the result type
may have to change. In the above example, the original `shape.shape_of`
op had a return type of `tensor<?xindex>`, but the folded attribute
(materialized as a `shape.const_shape` op) must have a type of
`tensor<0xf32>` to be valid.
This commit fixes tests such as
`mlir/test/Dialect/Shape/canonicalize.mlir` when verifying the IR after
each pattern application (#74270).
dbb782dffd