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/EntryPoint.cs

@@ -218,6 +218,7 @@ namespace Content.Client
             IoCManager.Resolve<IOverlayManager>().AddOverlay(new ParallaxOverlay());
             IoCManager.Resolve<IChatManager>().Initialize();
             IoCManager.Resolve<ISandboxManager>().Initialize();
+            IoCManager.Resolve<IClientPreferencesManager>().Initialize();
         }
 
         public override void Update(ModUpdateLevel level, FrameEventArgs frameEventArgs)