Adding creation of data into data handler, marking the way for szdb handling

SzCore/ISzFileManager.cs

@@ -1,3 +1,4 @@
+using System.Security.Cryptography.X509Certificates;
 using SzCore.DataObjects;
 
 namespace SzCore;
@@ -10,4 +11,5 @@ public interface ISzFileManager
     
     public bool SaveFile(string path, string fileContent);
     public string? LoadFile(string path);
+    public bool DeleteFile(string path);
 }