Admin - User Assignment: Improvement for a wider rollout

[kreibaum]

Here are the changes I want to implement before handing out the permission to more people than Bas. This is based on Bas experience working with the tool.

As this is for an admin only data fixing tool that is already technically usable, the priority is quite low.

• [ ] The audit table should be better. Right now it will store both sides, even if just one side was update. This means the exact change isn't always clear.
• [ ] You should be able to undo your last few assignments for a while. (Each row already has an id.)
• [ ] It must be clearer which slot is white / black.
• [ ] Pasting into the ID fields must work.
• [ ] The "ID Fields" should also accept user names and perform a search.