feat: add memorial arena

Common/Data/Excel/ExBossMonsterDataExcel.cs

@@ -0,0 +1,16 @@
+namespace KianaBH.Data.Excel;
+
+[ResourceEntity("ExBossMonsterData.json")]
+public class ExBossMonsterDataExcel : ExcelResource
+{
+    public int BossId { get; set; }
+    public override int GetId()
+    {
+        return BossId;
+    }
+
+    public override void Loaded()
+    {
+        GameData.ExBossMonsterData.Add(BossId, this);
+    }
+}