refactor: models use guids as PKs now

Models/Database/Player.cs

@@ -2,10 +2,10 @@ namespace GamificationService.Models.Database;
 
 public class Player
 {
-    public long Id { get; set; }
-    public long UserId { get; set; }
+    public Guid Id { get; set; }
+    public Guid UserId { get; set; }
     public Rank? Rank { get; set; }
-    public long RankId {get; set; }
+    public Guid RankId {get; set; }
     public int Experience { get; set; }
 
     public ICollection<PlayerMission> PlayerMissions { get; set; } = new List<PlayerMission>();