Refine "Use for grading" option to select "only for this student" or "for entire team"

[blerner]

Scenario:

• Alice and Bob and Clyde are teamed together, and submit a homework.
• This team was a mistake, and actually Clyde and Danielle are working together. Before the homework is due, the ABC team is dissolved, and an AB team and a CD team are created. Now Alice and Bob have abnormal submissions.
• Clyde and Danielle submit a homework.

To fix this, a professor has to mark the homework as used for Alice. This marks it used for both Bob and Clyde also. Then the professor has to find Clyde and Danielle's actual submission, and mark it used for Clyde again.

A simpler workflow would be to enhance the dropdown menu item to "Use for grading for Alice only" or "Use for grading team", instead of the current "Use for grading (implicitly the team)"