[WOBS-3151] - Support Community TagesWoche | added info about publicatio...

- [x] - added info about publication that user registered with, to User.php entity. This way we can distinguish for which publication user registered.


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- [x] -[WOBS-3151] - Support Community TagesWoche - Issue with banning users from commenting.

***Problem:***
In user profile (on dashboard - frontend) user have has ability to change `First name`, `Last name`, `Email address`, `Username`.
When admin wants to ban the user from commenting in backend (`Content -> Comments -> Ban/Unban user`) he/she has a few options to ban user:
- by username
- by email
- by IP address

***Sub-problems:***
1. If admin will ban user by `username`, after ban, this user will be able to change his/her username in his/her user profile (on dashboard) because `Username` filed is writable (it's normal input)
2. If admin will ban user by email he/she will be able to the same that described at point 1.
3. If admin will ban user by IP, user will be able to write comments, of course if he/she has dynamic IP.
4. If admin will ban user by random types, situation at point 1. will happen.

***Conclusion:*** User will be banned while he/she will not change his/her settings in dashboard. Banning system is useless in this case.

***Fix:***
To fix this issue, `username` text field in dashboard has been removed and username. Nickname can be displayed in dashboard only as a plain text - it won't be submitted to the database. That means, user can't change his nickname to make ban system fully working. (confirmation process is not affected by this change since username field is disabled only in Dashboard Controller)

E.g. if admin ban user by nickname, this user won't be able to change his nickname, i.e will be permanently banned from posting new comments (until he/she create a new account).


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- [x] -Change `First name` and `Last name` in user ban settings (`Content -> Comments -> Ban/Unban user`) to username. (If we ban user first name and last name we can ban other names and surnames and user will be able still to change his first name and last name)