Added IPersistanceManager.cs

src/Banquale/Banquale/Model/IPersistanceManager.cs

@@ -0,0 +1,15 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Banquale.Model
+{
+    interface IPersistanceManager
+    {
+        (List<Client>, List<Transactions>) ChargeDonnee();
+
+        void SauvegardeDonnee(List<Client> c, List<Transactions> t);
+    }
+}