[Speedgrader] Undo or cancel a Redo request after reassigning assignment.

[Tasha_Biesinger]

If an instructor accidentally clicks the "Reassign Assignment" button in SpeedGrader, there is not a way to undo the action. Please provide an option to undo the action.

Here is the link to the "Reassign Assignment" functionality:

https://community.canvaslms.com/t5/Instructor-Guide/How-do-I-reassign-an-assignment-in-SpeedGrader/t...