Make Username visible if can_see_sensible_data ist true

[Elblinator]

Current behaviour:
Even if a person is allowed to see sensible data the Username in the participant-list will never be displayed

Reproduction:

1. login as an admin
2. navigate to a participant list
3. create a participant without surname and firstname and only username; save
4. navigate back into the participant-list
5. User ## will be displayed in the participant-list

Wanted behaviour:
Given that a participant has the permission to see the username:
In the participant-list:
The display should be like the display in the account list
account-list:

participant-ist:

(description: the username should be displayed under the other name, if vote weight is activated then the username should be on the most left hand side and vote weight and name should be separated with a middot)

Several snackbars, views or pages:
with diverse actions you can see the string "User ##" so far I cannot identify an actual loss of functionality IF the username is also additionally displayed in the participant-list. this may need some revisiting after the participant-list is fixed. But this should be done is a separate Issue then.

[reiterl]

I tried to add the operator and a perm check to the getName method in user-repository. But it broke the app.
The login screen was no longer visible. I wont continue here.

[bastianjoel]

This is intended behavior. See for reference #3464.
The reasoning to remove the username from displaying as fallback was that in real instances first and lastname are normally always set.

[bastianjoel]

If you still want to change this see #3489

[jsangmeister]

I second that this is not necessary. Users with can_see_sensitive_data can still see the usernames on the detail page of the user. Implementing a permission check in the user repo does not sound feasible and workarounds or alternative solutions will require more work than what this issue is worth.

[Elblinator]

(23.04.24)
I updated the wanted behaviour