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

SzCore/ISzDatabaseHandler.cs

@@ -1,6 +1,15 @@
+using SzCore.DataObjects;
+
 namespace SzCore;
 
 public interface ISzDatabaseHandler
 {
+    public bool InternetAllowed { get; set; }
+    public Dictionary<string, string> SzDbUrls { get; set; }
+
+    public Task<SzDataset?> TryRetrieveDatasetAsync(Guid uuid);
+    public Task<ISzTemplate?> TryRetrieveTemplateAsync(Guid uuid);
     
+    public SzDataset? TryRetrieveDataset(Guid uuid);
+    public ISzTemplate? TryRetrieveTemplate(Guid uuid);
 }