Sort assignees and reviewers by name
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## Proposal
In https://gitlab.com/gitlab-org/gitlab/-/merge_requests/142519 we're changing how Assignee sorting works on work items, which will include epics (with Assignee as a new feature), issues, tasks, etc. Previously Assignees were sorted by user ID, which is not likely known by many users, giving the appearance of a randomly sorted list. Now Assignees are sorted by the displayed name giving users the ability to follow the sorting if needed to find a name. This also follows Labels sorting behavior, which sorts on label name (w/ scoped grouped).
**Merge request** **assignees and reviewers** appear to also be sorted by user id. **Sorting these by name** will bring these widgets into alignment and provide a more logical sorting for users to follow.
| Before | After |
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