Mark solutions as ungraded if no feedback options are selected
Currently the view logic is that if feedback/remarks have changed, then we should save the feedback/remarks and update the graded_by/graded_at info.
However, this allows for the case where a solution may be marked as "graded", but have no feedback selected.
When saving, we should ensure that at least one feedback option is selected, and if it is not, then the solution should be marked as ungraded.