Mostly backend models stuff

Changed some models, did some work on database, created a class diagram.

KTUSA PS/Controllers/TestController.cs

@@ -15,6 +15,9 @@ namespace KTUSA_PS.Controllers
     public class TestController : ControllerBase
     {
         [HttpGet]
-        public bool Index() => true;
+        public Object[] Index()
+        {
+            return this.HttpContext.User.Claims.Select(x => new { Name = x.Type, Value= x.Value }).ToArray();
+        }
     }
 }