same sparsity pattern, but with new provided values. It is similar to the
    `with_values` function of `RaggedTensor`.
*   Adds `StatelessCase` op, and uses it if none of case branches has stateful
    ops.
*   Adds `tf.config.experimental.get_memory_usage` to return total memory usage
    of the device.
*   Adds gradients for `RaggedTensorToVariant` and `RaggedTensorFromVariant`.