fix(federation): show team names to remote team members

[benjaminfrueh]

Team cells in federated tables showed Deleted team <id>, because the sharing instance had no user to look up the team as. Now the remote share receiver is used for the lookup, so remote users who are members of the team see its name.

Also renamed the misleading Deleted team <id> label to Team not found. This covers every 404 case where the team can't be found for the user, such as deleted teams or missing access.

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