This function is responsible for rendering the operations for the
widget deriving from dataseq. Specialize this function to provide
custom operations rendering. Default implementation is implemented by
'dataseq-render-operations-default' function.

Note, this function should take special care to respect
dataseq-wrap-body-in-form-p because its return value determines
whether the item ops should render their own form or they're already
wrapped by a form of the widget.