More granular private mode

[Desdaemon]

Private mode can already be turned into singleplayer mode; another requested option is to have it configurable to hide just friends, or just party members

[AdamWeb137]

Hello, I have made a commit for this issue in my fork of ynoserver, but I am unable to test it because the server is throwing errors because the tables aren't set up. Could I get the DDL to create the tables, please? Thanks.

[Desdaemon]

@AdamWeb137 If you could make a PR, I'll apply it to the test server later this week.