Add reassignment confirmation modal

Everyone can contribute. Help move this issue forward while earning points, leveling up and collecting rewards.

• Close this issue

Problem

We decided that group Owner should be able to re-assign placeholder contributions to any user existing on an instance. In case of .com, that could lead to mistakes and assigning contributions to incorrect users. For the reassignment to happen, the user needs to accept the reassignment request, however we should help group Owners to avoid mistakes as much as possible.

Proposal

In #466118 (comment 1994274911) we discussed adding a reassignment confirmation modal.

Design