Currently instructors are treated as all-seeing, always.

Instead, let instructor be all-seeing if they have no assigned registration sections (when viewing a graded by registration section gradeable) or no assigned rotating section for that gradeable (when viewing a graded by rotation section gradeable). But if they have assignments, treat them like a full or limited access grader and just show them what they are assigned.

This will be more convenient for a TA who does grading, but needs to take on some administrative roles.