Added preferences backend (#465)

* Added preferences backend

* Gender -> Sex

* ClientPreferencesManager properties

* Username validation

* Fixed client init

* WIP db

* Actually working sqlite db

* Dropped shitty sqlite libraries, dropped DbUp, added MigrationManager

* Added profile deletion, test

* Docs, sanity, tests, cleanup

* Cleaned up profile and appearance, fixed running on .net core

Co-authored-by: Pieter-Jan Briers <pieterjan.briers@gmail.com>

Content.Client/ClientContentIoC.cs

@@ -25,6 +25,7 @@ namespace Content.Client
             IoCManager.Register<IEscapeMenuOwner, EscapeMenuOwner>();
             IoCManager.Register<ISandboxManager, SandboxManager>();
             IoCManager.Register<IModuleManager, ClientModuleManager>();
+            IoCManager.Register<IClientPreferencesManager, ClientPreferencesManager>();
         }
     }
 }