add generic get/set data method to user class

ReallifeGamemode.Server/Entities/User.cs

@@ -1,4 +1,5 @@
 using GTANetworkAPI;
+using Newtonsoft.Json;
 using ReallifeGamemode.Server.Models;
 using ReallifeGamemode.Server.Services;
 using ReallifeGamemode.Server.Util;
@@ -161,5 +162,20 @@ namespace ReallifeGamemode.Server.Entities
         {
             get => NAPI.Player.GetPlayerFromName(this.Name);
         }
+
+        internal T GetData<T>(string key, T nullValue)
+        {
+            key += "data_";
+            if (!Client.HasData(key)) return nullValue;
+            return JsonConvert.DeserializeObject<T>(Client.GetData(key));
+        }
+
+        internal T GetData<T>(string key) => GetData<T>(key, default);
+
+        internal void SetData(string key, object value)
+        {
+            key += "data_";
+            Client.SetData(key, JsonConvert.SerializeObject(value));
+        }
     }
 }