Sparse tensors are always ranked tensors. Encodings cannot be attached
to unranked tensors. Change the type constraint to `RankedTensorOf`, so
that we generate `TypedValue<RankedTensorType>` instead of
`TypedValue<TensorType>`. This removes the need for type casting in some
cases.
Also improve the verifiers (missing `return` statements) and switch a
few other `AnyTensor` to `AnyRankedTensor`.
This commit is in preparation of a dialect conversion commit that
required fixes in the sparse dialect.
77f8297c6f