Mattermost-server: [Help Wanted] [PLT-3470] Update formatting of user lists to include both full name and nickname

[esethna]

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Notes: Jira ticket

Update the user list formatting in the Direct Messages "More" Menu, Channel Add Members and Channel Manage Members, Team Manage Members and System Console users pages to include both nickname and full name.

The format should be as follows (see screenshot):
@username - full_name (nickname)
email address

If full name isn't filled out but nickname is, the format should be:
@username - nickname
email address

[jsfeb26]

I'll work on this

[esethna]

Closing as done.